Gravity + Collision Detection

Hey guys!
Working on a small project, and it’s so close to working, I can taste it!

Problem is, it’s a bit of a mish mash of code from various tutorials on this site, and although I understand 90% of it, I can’t quite get it to do what I want.

Basically, everything works except the collision part…which still works, but not how I want.
The major issue is: Some items overlap when the collide, others don’t.

If you play around with it, you’ll hopefully see what I mean.
Any insights would be greatly appreciated!