Check out this excerpt from PrimeChoice Autos (http://www.primechoiceautoparts.com/t-Hub-Assembly-Hub-Bearing.aspx)
The Hub Assembly or Hub Bearing offers certain advantages over the Wheel Bearing. It’s an easy decision if you have a bad wheel bearing; if you have the option of purchasing a Hub Bearing Assembly vs. a Wheel Bearing buy the Hub Bearing Assembly.
Firstly, don't buy an individual bearing, you'll have to press that in yourself. Which seems painful just to think about it. Dirty fingers.
The Hub Bearings primary component is the wheel bearing. The wheel bearing is a precision machined component which is integral to the safe and comfortable ride of your car or truck
The hub assembly is a housing that has the wheel bearing and hub already pressed into it. Installation consists of removing the defective or worn hub bearing and bolting the new Hub Bearing Assembly to the knuckle.
So in a nutshell there's a difference between the two, the Hub Assembly is less stress and pain to install. Thanks to Prime Choice Auto for the explanation
I'll also be trying to install this at home, should be a lot of fun, will be my first big install.