Erlang is a system and language for distributed (not just concurrent) programming. Go is a language for concurrent (not distributed) programming. Unless things have changed substantially since I last investigated Go, the language does not sit within a system designed for distributed computing. There are libraries you can use, but the language itself does not attempt to solve the same problems as Erlang.

If you use Erlang within one node, it's roughly equivalent to Go. But Erlang is designed so that the same concurrency mechanisms you use on one node also work across a cluster of nodes. There are more differences than this, but this is probably the most critical one.