Fill - does just that - fills the inside of the object.
The Fill Panel gives you choice of kind, texture and edge.
Kinds of Fills
A few of the Textures
A few of the Patterns
Edge can be Anti-Alias (default), Feathered, or Hard.
It is the combination of all these elements that produces the finished effect.
For example:
results in this:
or this:
results in this:
Note the texture stayed the same, but the Kind of fill and the Edge changed.
