Two types of B763?
 

When I look at aviation photos, I see two kinds of 767-300's and I get really confused.

First kind:

http://upload.wikimedia.org/wikipedi...denstein-1.jpg

Second kind (stretched?)

http://www.visitingphx.com/alphal763.jpg

What are the differences (other than size) of these two? I don't think it's -ER or not, as both are ETOPS configured, looking at the nose gear doors.

There is no difference in size between the two. They have a different door/exit configuration.

HA has some 767's that came from LTU and DL.

there are different requirements for exit types/counts/arrangements based on seat counts

see FAR 25.807 here