Thread:Marvelus/@comment-26838855-20190116120806/@comment-26838855-20190502201633

The Russos have said they're alternate timelines. It's the same as Agents of S.H.I.E.L.D. other than the fact that in Agents of S.H.I.E.L.D., the "main MCU" is the new timeline, whereas in Endgame the "main MCU" is still the original timeline.

It's more out of necessity for labelling things rather than an actual in-universe difference.