Sketching an elf and a dawrf side by side gives a good perspective of each of the characters sizes and body shapes.

As for the elf on the left below: She is tall, slender and graceful, quite like the ones you might witness in Lord of the Rings. They're known for their air of grace and use of magic as well as their gentle and calm nature so I have drawn her with big, soft eyes and curved features. 

The dwarf on the right below is much shorter than the elf with blockier features and an overall more rough appearance. Dwarves are known for their short height but quick temper and manly features. Because of this I have drawn him a lot wider than the elf to show his muscled body. His features are more box-like and less curved like the elves.