Counter-Strike GO is, in my opinion, a seriously redesigned CS:S.
There is a gap of 7 years between the games, GO itself was developed for 3 years and during this time the VALVE company tried very hard to surprise those who had already played CS:S and attract new players. The engine is still the same Source, but with an updated graphical side. It’s surprising that the system requirements have not changed at all and the game practically does not slow down on weak computers. Also, a “Competitive mode” was introduced into the game, where the player and his friends in the lobby are automatically matched with opponents based on their level of play