That's why you go to the airline's page and cross check with your flight seat map. Easy to do. United has 4 subtypes for 777-200. By going to my reservation and cross checking with aerolopa I knew exactly which version I'll be flying on.
I stopped going to seatguru when they added the option where you had to put your flight number. I hated it. Before you could simply click on the airline and select subtype.
I'm happy with aerolopa maps. I agree that maybe they should make small visual distinction for seats with "no window window seat" or no under seat storage or limited recline etc. Until someone comes up with better maps, I'll be ok using aerolopa.