There’s certainly cross-pollination between characters and some story-arcs, but you know, the first movie is very clearly Avengers: Infinity War and, in time, we will reveal what the second film is.
Back in October 2014, Marvel Studios announced that they would be making the third and fourth installments of their Avengers series back to back, and that they would be called The Avengers: Infinity War Part 1 and Part 2.
This changed very recently, with the first movie being called The Avengers: Infinity War, and the second now being untitled — and many fans have been curious why.
For now we know absolutely nothing about the fourth Avengers movie, and that’s actually kind of refreshing.