I know they give skins and all but whatâs the difference? Can they only be used by the specific faction? Are there different stats for each factions gear?
Different gear types are from different factions. Usable by all but focusing on different attributes. for instance, lots of the eldrich focus on healing/health buffs, jenneret have attacking focused buff etc.
Short version: you can get skins & taunts for that factionâs characters, and as @LadAussie said, the gear associated with a certain faction will only contain certain attributes. ie: most LLC gear has effects relating to shields or buildables. Anyone can use it, but those crates help you narrow down the kind of gear youâll find if youâre after particular stats.
Long version:
Ok. That makes sense now. But wouldnât you just match the factions gear with factions characters? Seems like each factions general focus is certain traits anyways. Jennerit lean on attack and so on
To a degree, but the characters within each faction are so varied that itâs hard to make those stats line up nicely across the board.
eg. UPR gear gets a lot of reload speed or âafter completing a reloadâ effects. Those are awesome for Oscar Mike, Benedict and Ghalt, who reload all the time. Galilea and Montana never reload, though, so that gear would be worthless to them.
It might also be worth noting, that mali (negative Stats) are also faction-based. And a negative affix equals lower activation cost. You can actually use this to make more cost-efficient gear loadouts, by taking negative affixes, that donât affect your character 
I agree, that kind of mali is really important, since for example for Eldrid itâs usually something about shield (recharge rate, shield capacity, shield recharge delay), and you donât have a shield as an eldrid, so the only effect those eldrid gearâs mali have on eldrid character is to be able to buy their gear for smaller shard cost, which is in the end only a bonus instead.
@djbarnsley iâm glad I read your Post. In the Beta I was thinking I could not wear faction gear that was not my faction so I was deleting all faction gear because I did not remember what faction I belonged to. Now I learnt everyone can wear the gear so I will concider keeping it. 
You linked my thread! 
I feel so popular.
@jediskills83
As was implied, Knowing the factions can help you hunt for traits you want, or avoid negatives you donât. If youâre really looking for gear with more healing received/more health to put on your Montana, then Eldrid gear might be the way to go. If you know that you donât care about healing, then Rogue gear has a few healing-based negatives. If you really really want that âKillerâ attribute, you have to get Jennerit gear.
Knowledge is power. 
Good info for those who didnât get a chance to try out all the different crates in beta. The only thing I didnât quite understand is why the crates had such a drastic difference as far as the command level you had to be to unlock them, I think Eldrid unlocks around level 8 and then Jennerit doesnt unlock until around level 30 if I remember, which just seems like its obviously the best gear but I never got to the level to open any to see what kind of difference there was.