ALL B737NGs (including EI-DLX) have overwing exit doors, which open springloaded upwards. When the B737NG was designed, tthe FAA decided that they wouldn't allow the old plug type door used on the B737 classic anymore (
AFAIK based on the Manchester disaster), as too difficult to handle for people not used to it in an emergency.
I could be confused about model types here (excluding the -200 legacy).
I had understood that the standard plug type doors continued on the 737-Ng's until the passenger to door ratio crept up so as to require boeing to either limit the seating or to add additional doors. Boeing then submitted a plan to go to pop up doors as an equivalent safety. This was then published in the Federal Register for comments. I placed in the record a support for the Boeing proposal on the basis that it would indeed save time by ensuring that the new pop up doors got out of the way far quicker than the average passenger could read and comprehend the old style door instructions.
I stand to be corrected in the history of the Ng family