Last night my dad went to a pet store... He's very impulsive, and apparently has a liking for turtles now. He bought me a softshell turtle. Now, I don't have much of a problem with this- he's adorable! But I don't know what kind he is! So far, I've narrowed it down to either a smooth softshell or a spiny softshell... But the pictures on the net look SO alike to me. So, my question is:

What is a distinct trait I can look for to accurately identify this turtle?

Any other advice on keeping one would help... I.E. food, lifespan...

Thankyou!
(If this seems familiar, it's not spam, I just posted on another forum here on kingsnake. )