Mark vs Adapt for a Region
 

Hello All,
I am configuring a small circular vapor bubble in liquid water, 2D Axisymmetric. I have gone to Adapt>Region. Clicked on circle and enter my dimensions. I was told to hit Mark instead of Adapt when I was finished. I do not fully understand the difference between the two. If someone can explain it to me, I would be grateful.

Thanks,
Bradley