Srila Prabhupada - "Kṛṣṇa as His original childhood Form never leaves Vṛndāvana, all the Forms of Kṛṣṇa that appear elsewhere (the Vaikuntha planets and the material world) are His Viṣṇu tattva expansions."(BG, Ch 10 text 37)

Srila Prabhupada - "The original Lord Kṛṣṇa never leaves Goloka Vṛndāvana. All the plenary expansions are one and the same Viṣṇu-tattva however, there is no difference in Their potency." (SB, Canto 3 Ch 1 Text 34)

Krsna is likened to the original candle that lights all other candles of the same luminosity. 

Only Kṛṣṇa has all 64 qualities in full all the time, unlike all the other variety of living entities like the following-

1 - Visnu-tattva (Balarama, Visnu, Narayana, Maha-Visnu, Garbhodakashayi Visnu, Paramatma) exhibits 60 of Krsna's 64 qualities or 93.75% 

2 - Visnu-"sakti"-tattva (Radharani and Her eternal associates or internal potency also exhibits 60 of Krsna's 64 qualities also 93.75% 

3 - Siva-tattva (Lord Siva and his various expansions) exhibits 55 of the Krsna's 64 qualities or 85.938%

4 - The Jiva-tattva, (marginal living entities or individual jiva-souls) exhibits 50 of Krsna's 64 qualities or 78.125%. 

As said above, Krsna as His original infinite Vrindavana childhood spiritual Bodily Form, has 64 qualities of which 4 of those are unique to only Kṛṣṇa, only partially exhibited by some of His Visnu-tattva expansions.

Srila Prabhupada - "Kṛṣṇa is the original Supreme Personality of Godhead, and Baladeva (Balarama) is Kṛṣṇa's immediate expansion. Because Kṛṣṇa never leaves Vṛndāvana, all the forms of Kṛṣṇa that appear elsewhere are His expansions." (BG, Ch 10 Text 37)

Kṛṣṇa’s first expansion is Balarama, from Balarama all the other unlimited Visnu-tattva expansions expand from, each with their own unique name, spiritual Bodily 4 armed Form and Personality.

When the original childhood Vrindavana Krsna wants to enter the material creation to perform His pastimes in the Vrindavana, a facsimile of the spiritual world, it is one of His Visnu-tattva expansion who plays the roll of Kṛṣṇa in the material world.  

In other words, a Visnu-tattva tattva expansion performs those Kṛṣṇa pastimes or lilas in the material world.

In other words, because the original infinite Kṛṣṇa never leaves Vṛndāvana, His Visnu-tattva expansion (coming from Balarāma), plays the part of the original Kṛṣṇa in the material creation that includes killing demons there which does not happen in Krsna's Home in Goloka-Vrindavana the spiritual world.

When Kṛṣṇa wants to enter the perpetual Vaikuntha planets, or the temporary material creation, He first expands Himself as Balarāma (His older brother in Vṛndāvana Lila) and from Balarama, as said above, all Visnu-tattva (Visnu/Narayana Forms) manifest.

Visnu-tattva's (Visnu/Narayana Bodily Forms) are 4 armed expansions of Balarāma, Krsna's first expansion.

As said above, it is His 4 armed Visnu-tattva expansion who plays the part of the two-armed Krsna outside of the spiritual world (Goloka-Vrindavana) and within the material creation Vrindavana/Mathura facsimile of the spiritual world and kills many demons, such killing of demons does not happen in the original Vṛndāvana in the spiritual world, it only happens in the facsimile Vṛndāvana in the material world. 

All Visnu-tattva/Narayana expansion do not generally have those 4 extra qualities Krsna has unless they are playing the role of Krsna in the material world. 

The Krsna in the spiritual world who never  leaves there is always the Supreme Personality of Godhead and cause of all causes who can expands Himself into innumerable categories of living entities.

From Visnu-tattva, to Visnu-"sakti"-tattva, to Siva-tattva, to jiva-tattva (individual jiva-souls)

Of all the living entities, the ones who are almost equal to Krsna are called Visnu-tattva (Balarama, Maha-Visnu, Garbhodakashayi Visnu, Paramatma etc) and Visnu-"sakti"-tattva (Radharani and Her eternal unlimited associates)

While other living entities, the marginal living entities (individual jiva-souls), are "separated personalities who are independent from Krsna's absolute control due to having a mind of their own, or the freedom of self-expression who can voluntarily provide their own unique contributions to their relationship with Krsna, or reject Krsna if they choose. 

Such independent contributions or service by the individual jiva-souls actually deepens, expands and intensifies one's eternal relationship with Krsna. 

This allows individual unique loving voluntary contributions, exchanges and reciprocation with Krsna, that always exists on a "two-way" street of healthy exchanges and voluntary participation.  

Instead of being part of an impersonally controlled loveless dictatorship where the individual jiva-souls are always told how to think, act and serve and never encouraged the think for themselves by providing their own unique offerings or contributions to one's relationship with Krsna.  

Real surrender means choosing to voluntary build on one's unique individual abilities and then offer them as a personal contribution in the service of Krsna in a two-way exchange.

Love can never be one, there must be two.

Mindless so called surrender without personal  contributions in a two-way exchange, only denies and suppresses all personal voluntary independent contributions by the individual jiva-souls, resulting in the destruction of their unique individual personality and character, which is the bases of being the individual contributing person they are eternally as Krsna’s genuine servants, friends and associates.

This is what it really means to be an individual independent person (individual jiva-soul) who have a two-way relationship with Krsna just so they can experience loving exchanges. 

The individual jiva-souls always have their own unique independent personality, character and identity separate from Krsna's Personality. 

This allows the individual jiva-souls to express themselves independently including from Krsna in a two-way exchange the way they choose. This is includes even rejecting Krsna if they choose, without this quality of self expression, free will has no meaning.

So at all times, the individual jiva-souls eternally have their own unique abilities that are always expressed independently, this allows them to voluntarily contribute in a "two-way" exchange with Krsna, where the individual jiva-souls can think for themselves, and are never be told what to think or do by Krsna, this allows loving reciprocation, cooperative and voluntary participation to exist in a two-way exchange of feelings.  

The individual jiva-souls therefore, eternally have their own unique sense of self that allows them to be an independent thinking person who can express themselves in the way they voluntarily choose creating a two-sided relationship with Krsna, and not a one-sided dictatorship where one is always told what to think and do, denying personal contributions and self expression.

In the spiritual world, maya (the material energy), does not exist, so the individual jiva-souls can never be tempted by maya in the Vaikuntha planets or in Krsna's central Abode of Goloka Vrindavana to forget Kṛṣṇa.

However, the individual jiva-souls do have free will and that is how choices are made, to choose to stay with Krsna, or leave Him and go it alone by entering the temporary material world.  

Therefore, what eternally exist in the spiritual world is free will or the individual jiva-souls ability to express themselves in the way they choose, which is also the only cause of fall down from the Vaikuntha planets and Goloka-Vrindavana.

As a reminder-

Lord Siva (Siva-tattva), is neither Visnu-tattva or jiva-tattva (individual jiva-soul) but is in a league of his own with his followers, he is very merciful to the degraded extremely fallen individual jiva-souls who have become ghostly persons (frustratingly existing without a gross material bodily vessel)

All the different categories of living beings are Krsna's expansions, each having a portion of His 64 qualities however, only Kṛṣṇa has all 64 qualities in full.

Visnu-tattva and Visnu-"sakti"-tattva expansions have 60 of Krsna's 64 qualities which is 93.75%. 

Siva-tattva expansion has 55 of Krsna's 64 qualities which is 85.938%.

Jiva-tattvas (individual jiva-souls) expansions have 50 of Krsna's 64 qualities which is 78.125%.

Being all-powerful and the cause of all causes, Krsna can expand Himself into unlimited Forms with the same power and characteristics He possesses, without diminishing Himself in anyway.

Krsna as His original eternal childhood infinite Form, never leaves His Home, Goloka Vṛndāvana, therefore it is a Visnu-tattva expansion who enters the material world and plays the role of the original Kṛṣṇa in the earthly Vṛndāvana facsimile of the spiritual world.×==×.