Was just browsing some websites and I am a little confused. Can anyone tell me what's the difference between a jelly roll, honey bun, and a layer cake? How much quanity do you get and so on?

Jelly Rolls are 2 1/2" strips, honey buns... I think they are 1" strips but could be wrong about that one, layer cakes are 10" squares. Usually they have 30 - 40 fabrics in each pack. Hope this helps.

Honey buns are 1 1/2" strips.
Quantity also depends on the brand. There are some jelly rolls that only have 20-24 strips.
There are also turnovers that are 6" triangles, and Moda now has candy bars that are 2.5" x 5" rectangles.

Most charm packs are 5" squares :D:D:D

Clotilde.com has some of each in their close-out sale right now.

But they cost more than fabric by the yard.
Great if you don't like the cutting and don't mind paying a little more per yard.