Dragonball is the precursor to
Dragonball Z. Where in
DBZ Son Goku is an adult with a child of his own, Dragonball is the story of
Goku's own youth, the beginning of it all.
This includes his meeting
Bulma, his family history, his training alongside
Kururin(or
Krillin) under the
Turtle Master, and the beginning of his quest for the
Dragonballs. Among other things.
Dragonball has a significantly different style than
Dragonball Z: it is humorous and fun, with relatively little fighting. It is also filled with
perverted jokes, although
DBZ might have had the same before it was translated into a
kid's show.
All I know of the original Dragonball is from the
manga, I have heard that although there is a single movie which covers all of Dragonball, that it is horrendous in every way imaginable.