What are features of ANTLR that XText Does not provide?

I just came across very nice tool Xtext to create DSL as well as IDE for editing. I did some search on the web and found people saying it does not provide all the features of ANTLR. I am using ANTLR as my parser generator.

I am not even sure what features of ANTLR I will need to write complete parser for my language but ANTLR is around for quite a long time and probably supports more features than Xtext.

Can anyone please give some examples of what CANNOT be specified in a Xtext grammar?