Meteor JS backend vs Express JS
As of May 2017, I don't think anyone would choose Meteor's front-end (which is called Blaze) over the existing front end frameworks.
Meteor's backend, however, does seem to be more popular now with React as its front end. See Udemy for some fine courses on the subject.
Can Meteor do everything Express can?
Don't know. It can accept middleware, and do redirections, if that's what you're wondering.
What can Meteor do that Express can't do (easily)?
Meteor has MongoDB built-in, so you don't have to do your own mongoDB setup.
It talks to the front end using sockets, so if you want live updates of your data, you don't have to set up sockets yourself. When the database changes, your front end responds automatically - like a chat app.
Finally, it has a built-in authentication system, which saves you hours of time vs building your own login system in Express using passport or jwt, etc...