I'll give you generics. Statics, method visibility vs global/local/self. Interfaces, abstract classes, inner classes vs metatables. Data-structures apart from array are implemented on top of the language, array vs tables. Iterators are implemented on top of the language vs lua where they are part of the language. Checked exceptions can just be cast to Exception and ignored. Annotations are optional. Threads vs coroutines.

Yes, comparable to Lua. I'd probably not say it's smaller than Lua but I would say it's not greatly larger than it.