Boeing has offered two different window and exit configurations on the passenger 757s.
757-200 America West "Phoenix Suns" special livery
(collection)
The above photo illustrates the original "four-door" configuration, which consists of three full-size exit doors and one passenger service unit (PSU)-to-floor exit just aft of the wing. These doors are in identical positions on the opposite side.
United 757-222, San Diego 1991 (Andrew Abshier)
Some carriers, particularly those in the United States, have opted for the "three door" configuration, which deletes the PSU-to-floor exit in favor of two overwing exits on each side.