What is the difference between The Deep and the Abyss

[Semen Reaper]

Topic says it all, to my friends knowledge the Deep in his words is basically a ‘distilled version of the abyss that humanity uses’ dunno if that is true or not so I am asking what’s up with the two.

[spiritblossom]

depth is a deep place under the ground and the abyss is where there is nothing

[Artek [General]]

I never understood that one either.
Perhaps a translation mistake?

But the Deep does seem to be something unique, with ocean-like properties. When Deacons of the Deep start casting their unavoidable curse ♥♥♥♥♥♥♥♥ - the entire room gets this weird lighting like you are at the bottom of the ocean.
The abyss seems to be just black nothingness instead, if DS1 is anything to come by (Four Kings, Manus).

The spells that have something to do with the Deep also seem to have weird water-like properties.

Big shrug from me WTF is going on here. Im just sad we didnt get to fight any giant underwater monstrocities.

[Artale]

The Deep is a sea of humanity.
https://darksouls.fandom.com/wiki/The_Deep

The Abyss is basically the air to the Deep's ocean. It's "humanity run rampant".
https://darksouls.fandom.com/wiki/Abyss

I suggest reading up on both to learn more though.

[Scheneighnay]

Yeah, the deep is abyssal water

[The Fountaineer 🖋]

I always saw the Deep as the “true bedrock” of the Abyss, like the fundamental bottom, but that tidbit about it being the ocean vs the Abyss’s air quality makes sense too. It also spawns creatures that already exist as demonic/eldritch things where as the Abyss takes time to mutate and corrupt whatever it comes into contact with, which supports the idea that the Deep is like a more potent, sunken, primordial form of the Abyss.

A place beyond understanding. It ties in a lot with Bloodborne’s ideas of “the sea” and Aldritch’s visions of something bigger than the Age of Fire or Dark. At least with the age of fire, theres always the idea of Gods. With the Abyss, theres always men. With the Deep, everything becomes one.

[Le_Rieur]

https://en.wikipedia.org/wiki/Kegare

For me, if the Abyss are corrupted darkness by the First Sin, the Deep are the meaningless world without form (not the void, just the never born).

[Artale]

Lore-wise, the Deep is the dregs of humanity that seeped into the ground and pooled together (hence the 'sea').

"Dregs are the heaviest things within the human body, and will sink to the lowest depths imaginable"
https://darksouls3.wiki.fextralife.com/Human+Dregs

The deep was originally a peaceful and sacred place, but became the final rest for many abhorrent things. This tale of the Deep offers protection for those who worship amidst those horrors.
https://darksouls3.wiki.fextralife.com/Deep+Protection