ODAC is a bundle containing the Windows interfaces and the Oracle Instant client.
It's convenient if your a developer and also has some of the latest features such as VS 2012 support/ ODT for Visual Studio. etc.
Often the new features will appear in ODAC first .
The standard Oracle Client has more install options - It has instant client as well as administrator / runtime install options (which are not instant clients).
Those other install options can install additional components / utilities not featured in ODAC such as OraPKI (for wallets), tnsping, etc.
If you run the installer you can see exactly what gets installed in a full administrator install - for most deployment purposes you probably won't need
the majority of the components in the admin install.
11g Release 2 is older, and doesn't actually contain Entity Framework IIRC. The patched version to bring it up to 126.96.36.199 (which does contain EF) is available through the Oracle support website but not on the main download page for some reason. I have no idea why.
The ODAC download comes with the Instant Client, which I think will have everything you need. Not 100% sure on that though, I don't do Java these days. :)