Dwarves tend to be short, stocky and bearded, and dour expressions are their mood of choice. Elves are lithe and beautiful, mysterious and aloof. They have delicate features and speak in sing-song voices. Gnomes are similar to dwarves, but they're shorter and slimmer. Halflings are more like short humans with broad faces than like gnomes or dwarves.
Hobbits are the same as halflings.
Half-elves are, as the name implies, half elf and half human. They get the best of both worlds. Priest Priests are healers who have a certain amount of magical ability. Rogue Rogues tend to live for themselves. Wizard Wizards are the guys who have access to all the good spells, like magic missile or protection from evil.