Formal Italic

Formal italic, also known as a crisp italic will have sharp edges. Provides maximum horizontal to vertical line variation. Unless you are familiar with this type of nib it is probably best to try one before ordering one. It is also helpful if you have a "light" hand.

Stub

The stub is generally a more forgiving version of the italic. It has a larger radius making contact to the page. This will attribute to slightly less line variation.