>>212240332You'll get a lot of false answers because the early 00s yank fandom were very autistic and paternalistic old-school nerds who made a bunch of disinfo, rumours and half-truths accepted fact by repeating them enough times.
The simplest and more correct answer I can give is:
-Original TV series of 26 episodes, Neon Genesis Evangelion
-They didn't get to do quite what they were planning with the ending due to the production running behind schedule so as soon as the show proved to be popular enough, they pushed to get a theatrical project greenlit that would replace the ending of the show, Revival Of Evangelion, consisting of 2 movies
-Originally this would have contained some ideas that would later be used in the Rebuilds, but things ran behind schedule again and the project was reduced to 1 movie consisting of an hour-long recap clipshow with new addition scenes taking place at the time of episodes 21-24 of the original series, plus totally new alternate episodes 25 and 26 that take some ideas from the original TV ending and expand them
-The clipshow is called Evangelion: Death, originally packaged with a preview of alternate episode 25 called Evangelion:Rebirth, released as a preview for the finished project to apologies for delays as Evangelion:Death&Rebirth
-the alternate episodes 25 and 26 were then released together as End Of Evangelion, then the clipshow plus End Of Evangelion released together for a victory lap run as Revival Of Evangelion
-when released on home video, episodes 21-24 were recut with the new scenes from Death slotted in
-these new cuts and the alternate episodes thus replace episodes 21-26 of the original TV series and are denoted with apostrophes, 21', 22', 23' etc.
-so you now have two distinct versions of the show: TV ending (episodes 1-26), and theatrical ending (episodes 1-20 + 21'-26')