We killed USC on those little flares and bubbles.

Which brings up a terminology learning moment.
A screen pass by definition has to do more with the blocking. A screen is when you let the defense into the backfield and send lineman down to block at second level while throwing over or around the rushing D lineman, but completing the pass behind the LOS. This allows you to block downfield legally.

A tunnel screen is thrown to an outside receiver who is typically in twins or trips. The inside receivers block downfield and the outside receiver runs towards the QB, catching the ball behind the LOS. This can be done with lineman releasing as well, but usually not all of them. There are also fire screens and other screens with receivers that can go to the outside called bubble screens where the receivers run towards the sidelines/away from the QB (these routes can have blocking, but can also be run without blocking with the other receivers running downfield, making the defensive players commit to stay with them. You can run this route a few times and have the defense bite on it and then throw to a receiver over the top of the coverage.)

A Flare is when a back runs out of the backfield towards the sideline and then turns upfield catching the ball behind the LOS, but having forward momentum. This can be a primary call or part of a pass play with all kinds of options for the other receivers. This is not a screen play unless there is planned downfield blocking pre-pass and then the same route would be considered a bubble screen or something like that.

Of course, there are also a number of short routes that are run past the LOS by a few yards that are not screens. Just short passes.

These type plays are higher percentage plays from a completion standpoint. They also have a cumulative affect as they make the D Line have to chase sideline to sideline, wearing them down and not allowing them to key on a play. They also open up deeper passes as the Safety(s) may cheat going down hill on a formation after having to tackle a dude in open field all game.

Plays set up other plays and plays also are run for a cumulative affect on the defense. Keep that in mind when questioning an individual play.