What is the difference between next() and next('route') in an expressjs app.VERB call?

I hated it when I answer my own question 5 minutes later. next('route') is when using route middleware. So if you have:

app.get('/forum/:fid', middleware1, middleware2, function(){
  // ...
})

the function middleware1() has a chance to call next() to pass control to middleware2, or next('route') to pass control to the next matching route altogether.