What is the difference between an indent, and an evap?

Okay, so I took a frer this morning with fmu. At first, I thought I saw a super super vvvfl but I couldn't tell if it had color or not. I got upset, because I had gotten something similar last cycle (hours after the test) and got my hopes up, only for it to be nothing. So I opened the test to look closer, and I didn't see anything very definitive, so I threw it away. I looked later, and there was a kind of noticeable pink line. I know it isn't valid, but could it be something anyway? It wasn't too long afterward, certainly not hours this time. How can I tell if it is an indent or an evap?