As said above at the basic levels Java and C# are pretty close. Some of the stuff is a bit different like a Java for-each loop and a C# use slightly different syntax
Code:
for(Object obj: objects)
vs
Code:
for each(Object obj in objects)
Then at the higher level there are some differences. Such as C# being able to pass by reference, use pointers and have unmanaged code blocks. All things I wish Java would also support. C# can also have delegate methods which I'm not sure if Java can. Java probably can do it via Reflection but it'll be a lot sloppier to read. C# is pretty much just a mash of Java and C++ together to form a pretty good language. Sometimes the language is a tad verbose for me, though.