Eh, you got that backwards, Stormfury. Lolth was an intermediate goddess in Greyhawk but a major goddess in Forgotten Realms, in large part due to Drow being a more major power in the setting.
In 1st and 2nd Edition, deities like Lolth and Bahamut were active between campaign settings- the Lolth that Drow in Greyhawk prayed to was the same Lolth that Drow in the FR prayed to. This changed in 3rd Edition, when each of the campaign settings were completely sundered from each other and there wasn't any sort of connection between them any more. At that point, we had two campaign settings with deities that were identical in name and portfolio, but they didn't share the same experiences: if a particularly adventurous group of heroes ended up practicing a little deicide in one setting (and it became canon), it had absolutely no impact on that deity in any other settings.