I don't really know about this, Drow are subterranean race that live in the underdark. There was some kind of war that Drow fought Feywild lost and followed Lolith their, supposedly it was a big shocker cause Lolith doesn't have ties to whatever creature that made the underdark.
From what I understood you don't just leave underdark or abandon Lolith, you live underground dominated by a evil deity that rules that place with a iron fist. It's a cut throat society, where no other deity or anyone is going to save you. You don't get to just walk out and say F this.
Now if there is a group of surface drow that follows Eilstraee, there is probably a story behind it, hence why its separate, because of story. This is Forgotten Realms and it has lore from a lot of different media. Just like how you don't get to pick your origin which is only Baldur's gate.
*edit
After some digging and oh buddy there is a lot of lore to dig through with Lolith, Eilstraee, Darkelves, and Drow. So basically Drow are decendants of Dark Elves, supposedly look diffrent and there was a spell that was cast on Eilstraee followers. With this, yes the drow "dark elves" are going to look way different than the current drow we know (possibly having brown hair).
Sorry, Fallen, but this incredibly vague and nebulous set of details is largely incorrect or misinformed; some elements of it are vaguely true-ish, about as vaguely as saying "some kind of war", but in general, if your research doesn't get you to the point of consistently spelling the central deities' names correctly (Lolth, and Eilistraee), it's hard to give what you're saying much weight.
The Drow did not fight the Feywild; that's a place.
No-one 'made' the underdark, save those responsible for the creation of the entire material realmspace.
You do just leave the underdark, if you are a drow that develops a conscience or decide you cannot live within drow society any more, and you decide getting out is what you want to do, yes. You won't be able to come BACK, most likely, but getting out in order to flee to the surface is less of a difficulty for an individual drow to decide to do, depending on their rank and position (particularly important or valuable drow may have assassins sent after them, naturally).
There are a number of deities that you can turn to even within Drow society, besides Lolth. In Lolth-dominated communities, it's generally not a good idea to worship anyone else, of course, except in secret, but even Lolth only shares about an equal footing of worship with Vhaeraun, an equally evil and malicious deity who actually does promote gender equality and the importance of personal actions defining worth, rather than your particular squishy bits (don't misunderstand, he's every bit as dark and nasty as Lolth). Beyond those two, there are several others that drow may worship as well; Selvetarm has his share of direct followers, as does Zinzerena, and in secret there are yet many who do offer prayer to Eilistraee even while serving Lolth and the Lolth-driven society on outward appearance.
There is also a long history of various uprisings and resistance movements within the underdark drow society, such as those committed to ending Lolth's tyrannical rule entirely, or those seeking to break the religious stranglehold that her priesthood holds over much of their society, or even those who seek an abolition of slavery and slave-taking.
As mentioned, the whole "Eilistraee 'purified' the drow and magically changed their physical appearance to make them lighter skinned as a 'reward' for being good and as a form of 'salvation' because dark skin is inherently bad" is a construction of one particular series of novels which goes directly against virtually every other piece of relevant lore in existence on the matter and which Wizards have retconned thoroughly and disowned as applicable canon... and with good reason.
There are many drow the dwell on the surface, and many of them do indeed worship Eilistraee. They are not a race, or a subrace of people. They're just Drow. Who are Elves. Just Drow who made particular choices about their own lives, or who are the children or descendants of such drow.
As for the two types of Drow they went with, they did this for story element purposes. Certain dialogues are triggered based on whether you are Llothsworn or Seldarine.
As mentioned already in this thread, this is to do with the tag system, which, also as already mentioned, is more than capable enough, and indeed would have an easier time of handling this distinction and division if Drow were a simple, single subrace of elves, and payers could elect a deity regardless of class, as we should be ale to do.
The idea is, are you basically a good Drow or evil Drow?
And the very idea of baking that choice into a FACT of your RACE, that you are locked into from character creation, and have baked into you as part of your literal biology is absolutely freaking disgusting and no-one at all should be acting as apologist for Larian for doing this. It's positively VILE.
In THIS part of character creation, you are picking your biological race and subrace. Who you worship, and whether you are a good or evil aligned individual should NEVER be baked into this particular choice.
