Well my question real quick: How can you tell the difference between an Atemoya plant and a Sugar Apple plant? or the difference between the fruit(aside from taste)?

My scenario is that my girlfriend went to a local produce store. She isn't really a gardening type of person so when she went there to ask if they had any Atemoyas or Sugar Apples they said 'Yes, we do'. She ended up buying some fresh of the tree fruits and also bought a small plant. The problem is the folks there used the word Atemoya and Sugar Apple interchangably so I honestly have no idea which type of plant she got.

I looked at pictures of both online but it is kind of hard to compare them because they little nuances i see as differences could just be the way the plant grew in whatever enviroment. It would be great if I knew what it was just by the plant(it is about 2.5 feet tall currently) but I imagine that whatever fruit she bought will identify the plant since I am sure they raised this plant from seeds.