The fundamental difference (and there is one), is that Go omits the concept of inheritance, preferring composition instead. So in contrast to many mainstream languages today - Java, Obj-C, C#, C++, Ruby, Python, PHP , etc. there is no concept of inheritance, only composition of objects and conforming to interfaces.

There's a good quote in the article about this under 'Inheritance Is Best Left Out' - James Gosling responds to someone asking what he'd change in Java in retrospect - “I’d leave out classes,” he replied.