I've been using IntelliJ for years now. Are there any good websites or books on Eclipse?
I don't need to know what absolutely every single tab and feature does. I just want to be immediately productive and then have some more references to look up later.
Some good sources:
Add a "IntelliJ style mappings for Eclipse" and you are good to go.
The SO question "Things possible in IntelliJ that aren’t possible in Eclipse?" can help you spot more quickly some differences that you need to take into account during your migration process.