Originally Posted by cova

2. The 757 is an older aircraft in terms of when it was introduced. The 757 number is lower than the 767, 777, 787 number. The 757 aircraft was designed to replace the 727 and for mostly domestic use on longer haul routes. The 737 was for shorter flights. The 747 for long haul international (remember Pan Am used to be an all 747 fleet airline). Then the 767 came along (with same cockpit as 757) as a smaller international widebody and higher capacity domestic. And the 777 as a two engine to sort of replace the 747 plus serve higher capacity domestic and international.