What does the G after the number value mean for games for windows live achievements?

Here is an example:http://www.xbox360achievements.org/game/batman-arkham-asylum-pc/achievements/|||G = Gamerpoints|||the g stands for gamer score. the eaier the achievement, the less gamer score. the more difficult, the higher the gamer score goes.|||If it reads something like "25G," the G stands for gamerscore. The higher a player's gamerscore, the less n00bish the player usually acts.|||Gamerscore





i.e achievement unlocked 50 (g - Gamerscore)