For starters on is free and one comes at a cost (dotnetmushroom).

Both are tools to assist in the development of DNN modules based on the RAD approach - effectively both are a module frameworks.

Basically they provide a set of wrappers that give you quick tools to layout forms and handle standard core processes like - CRUD - if the module you want to build is built around forms and data entry into database tables then RAD tools can be a great way to get the job done fast.

HOWEVER - they are not always the ultimate answer to every project - it really comes down to what you want your module to do - for example - they are not really designed to help you build a new authentication provider - for example.

Westa