E: D doesn't have a master server either.
its p2p.
Not sure what the differences between "64 player dedicated servers" and p2p are. I know that the limit for the number of players in an E: D instance is 32 according to FD, but the most I've ever seen in the same instance is around 25.
As far as I know (which is by no means authoritative) it's a matter how much is P2P in the client and how much is server based.
Star Citizen originally advertised heavily server-based gameplay, however as time has gone by they have decided to hive more functions to the clients. ED is coming from the opposite direction - originally it was publicized as very much a P2P client-based game with only some persistent data held on a central server (or servers). This approach was modified substantially before the gamma release as FD experienced far more issues with networking than were anticipated. More functions were centralized and more server power brought in. This was at least partly the reason that an offline solo version was dropped - so much had been moved back to the servers that the game now needed a constant connection.
I don't think a definite number of players per instance was ever announced for either game earlier on, but 64/instance on SC and 32/instance on ED seems to be the accepted numbers now. ED's network matching system is also not at all like the instancing in many MMOs - they refer to it as "islanding" and it's a much more dynamic method - an island basically comprises a single player, but when players meet the islanding system might (usually does) merge their islands temporarily, and the limit of players that can be put into an island seems to be 32. The limit is often not met and players can't seem to force the maximum capacity. Maybe this is due to other network pressures in the area of space they are occupying and/or individual players' network access, and so the threshold is dropped to maintain adequate data throughput.
I have no idea whether SC will be using instances based on defined ares of space, or whether it will also use something like ED's islanding. I suspect the latter because it's hard to see how you could manage it otherwise in the vast reaches of space. It's entirely possible that SC might use a hybrid system that allows a large number of players in traditional instances for ground combat campaigns, when in space stations or cities, or anywhere else where the playing area can be defined and fairly small, but revert to something like islanding with a smaller possible "population" when play is in open space.
Games like, say, SWTOR don't have these issues because they use the traditional MMO method of defined areas with large population limits/instance, but then they don't have any sort of free-form flight system. EvE manages it's massive population in a single instance because it's not a twitch game, so the networking is hugely less of a load.
