Okay...here's the short answer;
The -300 is longer than the -200! Simple.
As for the exits, I thought they both had 2 small o/wing exits?
Anyway, the US registered 763's had to have the 2nd main door fwd of the wing for FAA requirements, rest of the world was satisfied with the o/wing ones.
Best way to tell a -400 is the raked wing tip.
