Hello Jen!
Jelly Rolls are typically 2.5 inch strips that coordinate all rolled up.
Charms are different fabrics usually 5 inch square.
Fat quarter is a piece of fabric 18 X 22 inch. Rather than cut a quarter of a yard it's cut longer and half the width.
If you go to Moda Bake Shop you can get tons of ideas! Moda came out with all the "dessert" type cuts.
Hope this helps. :D