People tend to get confused between repetition in patterns, which is understandable, as they both deal with repeated elements. But the similarities end there.
While repetition occurs when the same elements are repeated throughout a design, a pattern is composed of different components repeated in the same way. Think of the way gift wrapping is usually made up of a few different repeated elements—that's a pattern.
You'll also notice patterns commonly used as backgrounds on websites and in mobile applications.
As a general rule, it's best to use colours, textures and shapes to create patterns. Try to avoid doing so with words — it tends to just give folks headaches. Despite the occasional bright colours and wacky designs, the key to creating effective patterns is simplicity.