Is RubyMine a superset of WebStorm?

I have some Ruby on Rails projects and also some Node.js/AngularJS projects.

Does RubyMine cover all that?

Or does WebStorm have some JavaScript development features not found in RubyMine?

It isn't a huge amount of money for both licences so I'm not super stressed out about this.

I just want to avoid installing / configuring / maintaining more tools than necessary.