So... what is earth really?

 Other planets are round

According to Flat Earth Theory, the Earth and other planets are not really the same type of celestial body. To put it another way, which I'm sure everyone everywhere will take offense to, the Earth is different.

So what does that make earth. What are We living on?

Other planets are round

According to Flat Earth Theory, the Earth and other planets are not really the same type of celestial body. To put it another way, which I'm sure everyone everywhere will take offense to, the Earth is different.

So what does that make earth. What are We living on?

It makes it God's special creation made for human habitation. Your question is meta- physical and philosophical in nature along with questions such as "what is our purpose?".