Bhu-gola simply means a spherical or round global shape. So there are "three Earth" (Bhu-gola) descriptions in scriptures explained here.

Bhu-gola is a Sanskrit word that also decribes our "earth planet" as a "round global sphere".

It is NOT flat as some primitive religions and their less intelligent followers have claimed due to their nonsense ignorant version of their scriptures.

This also includes those who  WRONGLY believe Vedic texts claim our Earth planet is flat.

There are "three Earth" meanings to the word "Bhu-gola".

In the Srimad Bhagavatam (Bhagavat Purana) "Bhu-gola" simply means "spherical, round or a globe".

The earth planet we live on is a "round global sphere" existing in the ocean of outer space and is 7,917.5 miles in diameter, it is NOT flat Srila Prabhupada clearly tells us-

Srila Prabhupada - "On the ground our earth looks flat but when you go up you will see our Earth planet is a ball, a global sphere" (Lecture New York 1966.)

Also the Sanskrit word "Dvīpa" does NOT only mean flat Island, the word has two meanings -

1 - "Islands" or "continents"

2 - Round planetary globes or spheres situated in the ocean of outer space.

Srila Prabhupada - "The planets are called dvīpas. Outer space is like an ocean of air. Just as there are islands in the watery ocean, these planets in the ocean of space are called dvīpas, or islands in outer space" (Caitanya Caritamrita Madhya 20.218, Purport)

Furthermore, the word "Bhu-gola" is not only a description of our Earth globe, but also describes the shape of the massive outer Brahmanda universe, that surrounds and incases our smaller inner universe, with its 14 planetary systems in it, that exists deep inside the surrounding outer Brahmanda universe.

There are billions of these greater Brahmanda universes that all originate from the breathing and pores of the sleeping Maha Vishnu as seen in painting below.

Deep within each Brahmanda, also known as a celestial egg ("Bhu-gola") as seen in painting below, there is an inner smaller secondary universe.

The sizes of both the outer Brahmandas and there inner secondary universe vary in size based on how many heads the Brahma in each universe has.

Our universe inside our Brahmanda is considered small because Brahma has only 4 heads.

In other universes within other Brahmandas, their Brahma may have hundreds of heads, even thousands or even a million, yes, it is almost inconceivable to understand.

Our small universe deep inside our surrounding Brahmanda, is described as being 500,000,000 yojana (4 billion miles) in diameter.

And is often called "Bhu-gola" because it is also a round spherical universe inside the greater spherical Brahmanda.

"Bhu-gola" simply means spherical or round as a global shape. So there are "three Earth" (Bhu-gola) descriptions in scriptures. 

1 - The greater earth (Brahmanda) (Bhu-gola)

2 - The inner earth inside our Brahmanda is called "Bhu-gola" universe with its 14 Planetary Systems also called "Bhu-Mandala" 

3 - And "Bhu-gola" also refers to our small earth global sphere we live on within our middle planetary system called Bhuloka as well.

"Bhu-gola" describes the "Earth globe" as a round spherical planet, which is just a spec in one of the 14 planetary systems within our small universe also often called the Bhu-Mandala universe situated deep within the surrounding Brahmanda outer shell.

"Bhu-Mandala" is described in the 5th Canto of Srimad Bhagavatam as our inner material universe 4 billion miles in diameter inside our Brahmanda.

In this way, our small "Bhu-Mandala" universe with its 14 planetary systems, that is also described as "Bhu-gola", is surrounded by the greater "Bhu-gola" (Brahmanda) universe that encases our 4 billion mile diameter Bhu-mandala or Bhu-gola universe.

Therefore we can see that "Bhu-gola" means - 

1 - Our "Brahmanda universe" 

2 - The "inner secondary material universe inside the Brahmanda", 

3 - Our "Earth planet" within one of the 14 planetary systems that all exist within the inner secondary universe.

All the above are spherical like a ball in shape.

As explained, the size of our inner material universe deep inside our surrounding Brahmanda universe, is 500,000,000 yojana in diameter (4 billion miles).

One yojana is equal to eight miles.

Therefore 8 times 500,000,000 yojanas = 4 billions miles (4000,000,000 miles).

So our Earth global sphere (7,917.5 miles in diameter) we humans live on and is NOT 4 billions miles in diameter as some foolishly claim.  

Therefore our Earth planet CANNOT be Bhu-mandala according to the figures in the 5th Canto of Srimad Bhagavatam! 

There it says Bhu-Mandala is almost 4 billions miles in diameter (500,000,000 yojanas) and is a far too large description to be our Earth Planet or globe. 

Now the diameter of our outer greater Brahmanda universe (celestial sphere or shell of 7 material layers) is massive, it is 44 quadrillion 444 trillion 444 billion miles in diameter.

And that diameter can be just from the outer edge of our inner 4 billion mile diameter material universe.

This means the full size of our Brahmanda greater universe could be double that size according to some Vedic scholars.

In other words, if the measurement is taken from the outer edge of the inner 4 billion miles diameter spherical universe inside the Brahmanda, then the diameter of our outer surrounding Brahmanda shell is twice that size.*