here is a pilot's explanation of "fly by wire"
In light aircraft, there is a direct physical connection between the controls and the surfaces themselves. There are linkages, cables, bearings, push pull tubes.
This system continued into the bigger and bigger airframes by virtue of boosted controls. Think of how your car's power steering works.
Despite the immense size of the 747, that physical connection from the controls to the surfaces is still there. It is boosted and augmented by servo tabs and hydraulic systems.
With the advent of true "fly by wire", that connection is gone. Now you move an Atari joystick and a computer interprets your inputs and moves the surfaces for you. There are redundant systems to keep the blue screen of death from being literal
One of the things that Fly by Wire (FBW) allows is the ability to fly unstable aircraft. The F117 is one of those, the "wobbly goblin" would be unflyable without those computers.
The C-17 is fly by wire, and I did a couple of hours in the big sim at the nearby AFB. It could do things that were otherwise unpossible.
You could pitch up to 10 degrees up, press a little switch on that atari joystick ( seriously, it is a tiny little stick on a column ), and that 10 degrees was locked in for you. It moved a combination of flaps and ailerons and trim tabs to keep that pitch, even when you were moving the yoke to increase rate of descent, etc.
Trim set the airspeed.
It had a heads up display with an airplane shape on it, and you could add throttle and the plane would move down the runway, or cut throttle and watch your projected flightpath go short of the runway. We were doing landings on a 3500' strip with a light load, and I could pull it off with no big plane experience, thanks to the instructor and those wonderful tools that FBW gave me.
Back to the blue angels and formation flight.
When you are going in the same general direction, you can bump into each other without crashing. It's not commonly done, but it does mean that you can get closer and closer and train and work it out without fear of instant death like crossing the beams on ghostbusters.