Difference between door latch & finger loop spring?

[countrybound]

I'm making my first indoor quail pen. What's the difference between a door latch and a finger loop spring for a door that swings out?

Thank you in advance

 

[DarkWolf]

Finger loop spring...

Door latch..

 

[countrybound]

Sorry, I wasn't more specific...I mean the door latch & finger loop spring on this page (middle way down): http://www.bunnyrabbit.com/price/cagequip2.htm

Also, when is a spring w/ flat hook used (on the same page)?