While you data is correct airlines do code their planes differently to designate different aircraft and different configurations.
For example UA has two configurations of 757-200 aircraft but had/have 3 designations for etops vs nonetops and the different seating configurations.
Originally Posted by
dsdwe234sfd23
ICAO codes for different versions of the aircraft.
https://en.wikipedia.org/wiki/Boeing_777
772 = 777-200
773 = 777-300
77W = 777-300ER
Don't think the seat map is specific to only that abbr. The airlines have control over the seat arrangement, so knowing 77W and KE should be sufficient.
Never hears of 77I, but the 77L is a 777-200LR. Hopefully someone with more knowledge will reply.