hash_table vs unordered_map

Hi all,
  I'm looking into some refactoring activity while I'm waiting for
some merge reviews to be completed, and by idly browsing the code I
crossed paths with hash_table.

I was about to code a c++ templatized wrapper, but then I started
wondering what is the advantage of hash_table versus
std::unordered_map?
Would it be useful to refactor from one to the other while waiting such as now?

Thanks

-- 
    /kinkie