Rails is a bit more productive. Being a slightly more-expressive language, Ruby has a considerable edge when it comes to DSLs.

Whether it's worth it for you to learn or not depends on how quickly you can pick it up and how important the web app part is to you.

Edit: Why is yazmeya's sibling comment flagged? It's not a glib one-liner and it's clearly an attempt to be helpful.

I wouldn't recommend Rails as front-end only. It's fine as a full-stack framework, and rather nice for quickly building out a back-end API, but not really compelling if you're only using the front-end side of things IMO.

That said, I would argue that Ruby is a very similar but nicer scripting language than Python (particularly for general utility / glue scripts), so if you enjoy scripting in Python you would probably find Ruby easy to pick up and potentially a nice compliment to what you already know.

The neat thing about Rails is that going from zero to a running database-backed app is done in a ridiculously few number of keystrokes that invoke quite a bit of under-the-hood magic in terms of routing, form and view scaffolding, etc. Django is kind of similar, in that you don't need to write a ton of code to get a basic app in the browser, but it exposes a bit more of itself as you get going right away, and you need to work a bit connecting things together. As far as mature, large Django and Rails apps – the similarities outweigh the differences, in my opinion. I would recommend doing the basic Rails tutorial, it really doesn't take that much time.

Unless you are interested in learning ruby or have some specific gripes with how django does things (it is very opinionated) I would say no.

All web frameworks are equivalent.