While it's terribly exciting that Avengers: Infinity War is now just around the corner, it's easy to forget that we have ANOTHER huge Avengers movie coming in just over a year, which will arguably be even bigger.
Initially, of course, those two movies were presented as a double-header - both called Infinity War - but the decision was then made to split the titles and hide what Avengers 4 is going to be called, presumably until the end of its predecessor carries the message "The Avengers Will Return In..." That decision was made, apparently, because the films are very different, despite there being a big link.
And just to clarify/confuse that even more, Infinity War's writers Christopher Markus and Stephen McFeely have been asked whether they thought of them as one massive story, or two separate tales. Their response is as clear as mud:
Christopher Markus: Both.
Stephen McFeely: Can't have the second one without the first one. But our hope is that it's breakfast, and then lunch.
Markus: It does not feel like you hit pause, and then unpaused it. It is two very different [movies].
On the same subject - and while talking about the title of Avengers 4 with Empire, Anthony Russo called the second part "...the Question Mark film. It's more of an epic adventure in the classic sense, with huge emotional stakes." That suggests we're getting a different tone - and to be fair, Infinity War doesn't look like a caper (it's more like an intentionally devastating drama) - with suggestions that it will have elements drawn from horror movies.
Difference is absolutely no bad thing, of course and it's interesting to note how the writers and directors are approaching the distinction between the two movies.