Did you look at the doc for these two products?
In a nutshell, Community Builder is profile manager. It allows you to have more than just the simple name, username, password fields that are native to Joomla. Using CB, you can get all kinds of information from your members like where they live, likes, dislikes, etc. You can use our CB Login Redirect to key off different responses within a select field (City, State, Country, whatever) and direct them to specific URLs based on those values. You need Community Builder, however, to make this work. That is why it is Login Redirect for Community Builder.
The user group login works with your standard Joomla groups such as Registered, Author, Publisher, etc. It can also work with custom groups created using JUGA, JACLPlus, and some other user group permissions managers.
Have you read the doc on these two:
www.corshops.com/User-Group-Login-Redirect-Home-Page-Documentation.html
www.corshops.com/Login-Redirect-for-Community-Builder-Documentation.html