Each are virtually the same yet have different 'cool' features that the other may or may not have.
Your best bet is to go to the Autodesk site and read about each program and the feature list they have. You'll find a lot of them are the same.
Then search in these forums as there has been tons of topics on the two of them, usually mistakenly about which is 'better'. You'll quickly realise that neither is better as they are just tools to do a job.
Simon