There are quite a few different kinds of CFL Bulbs.
Here are the 3 most common types:
Spiral type:
This CFL bulb is probably the prettiest of the light bulbs. As the name suggests, the bulb is a spiral shape. It can vary in size, and is quite decorative on its own.
Standard Bulb Shape:
This shape, though it can vary, is a standard shape bulb, which is useful for areas where you would most likely use the old shaped bulbs. For example, in a chandelier, where a spiral shape would not do.
Straight CFL Light Bulbs:
This is probably the most common shape. These bulbs just look like short, thin tubes coming out of the base and going back in. These are most ocmmonly used outdoors.