Though I have approached this in a few ways before, I am left confused on the sub-races elves have. Referencing The PHB (P.23/24), DndBeyond, SCAG (P.106) and an Unearthed Arcana from WotC (Knowing it's experimental, but it will come in to play), there seem to be different ways to class Elves...
In the PHB, all elves, save for the Drow of the Underdark, seem to find themselves classed as either a High Elf (Bright or Dark) or Wood Elf, depending on if your elf comes from Greyhawk, Dragonlance, the Forgotten Realms, or Faerûn:
Grey, Valley, Silvenesti, Sun, Gold or Sunrise
High, Qualinesti, Moon, Silver or Grey
- Wild (Grugach), Kagonesti, Wood, Green or Forest.
However, DndBeyond goes even further by breaking these elves up by the regions of Aerenal, Valenar, and Eldrin, giving lore to each type of elves (and mention of a Hawk, Horse or Hound pet for Valenar as well), though I am not sure if this adds to the locations or are separate, as they have no additional names.
Then the SCAG and Unearthed Arcana introduces us to the Avariel (winged, or Bird), Lythari (lycanthropes, or Wolves), Sea (aquaman or Fish), Star (Etheral), Wild (Grugach), and Shadar-Kai (Shadowfell Zombies) and has different stat blocks for all but the Lythari and Star.
The first confusion comes with how often Wild Grugach elves have been mentioned as both part and separate to the Wood Elf Sub-race. Along with the separate section for the Arenal and Valenar (which can be either High or Wood) it makes me wonder how this all works:
Is Arenal and Valenar locations alongside Greyhawk, Dragonlance, Forgotten Realms, and Faerûn? or a category that encompasses them?
Are Eldrin, Avariel, Lythari, Sea, Star and Shadar-Kai separate from the High and Wood elf sub-classes like the Drow are? or can one find an Avariel Wood elf?
Do elves have separate traits within their subclasses? ie. do Grugach and Kagonesti look and act the same or have their own physical traits and way of life?
Simplifying everything together into one coherent thought, I would like to know how Elf sub-races work given all the official information that is published and what racial-traits makes each kind of High, Wood, etc elf type unique within its sub-race.