Fiberglass mat or cloth

I am about to embark on my first fiberglass box, and needed some advice from the pros.  I understand how to resin the mold, and then lay fiberglass mat down and resin over it.  My question is, what is fiberglass cloth?  Is it the same as the mat, but easier to work with?  Can I lay it down on the floor and around the humps of my car to lay the first mold?

I guess my question is: is the fiberglass cloth (looks like a tarp weaving) and the fiberglass mat basically the same thing?

Thanks in advance.

the mat is alot thicker than the cloth is.  also the cloth is woven fibers, while the mat is chopped and pressed fibers i believe.  i myself prefer the mat, although the cloth is a little cleaner.  when im done using the mat ive got little fibers everywhere.