How does D's templated functions implementation differ from generics in C#/Java?

[aberba via Digitalmars-d-learn]

Syntactically they look the same (although D's can do more 
things) so I'm trying to understand how why in D it's called 
template but in languages like C#/Java they're generics.

I guess I have fair understanding of D's code generation but 
isn't it same as what what is available in those languages too? 
How are the implementation different?