TP takes place 100 years after OoT- And according to the manga, the Zelda in TP is a reincarnation of the one in OoT (now I know the manga isn't canon to the games, but it does go further into detail about some things and I believe it is still a good reference for Nintendo canon, especially considering Nintendo themselves suggested some of the extra details). TP Zelda doesn't realize who she was before until reading a book of Hyrule's history and then remembers OoT's events and her past life when she realises she wrote the book herself. I'll take some pictures of the dialogue though, because I'm not 100% sure whether TP Zelda is OoT Zelda or if she simply gains OoT Zelda's memories from being connected through the triforce.
Here are the pictures from the manga. Ganondorf implies that the Zeldas are not the same, but then Zelda corrects him (I think. I can find the manga a bit confusing at times...) But I know the authors are trying to tie it in with their OoT manga from '98, because Zelda has a flashback to a panel that's from the OoT manga (Should have taken a picture of that too, come to think of it, but whatevs). Sorry if the pictures aren't the best quality, I had to scale them down to upload. PS, the pages are ordered 4,3,2,1 because you read them from right to left.
So according to this canon at least, TP Zelda is the reincarnation of OOT Zelda.
This ties into a theory/headcanon I have that Tetra doesn't remember being Zelda after the events of Wind Waker. Like, Zelda locked a part of herself away to only be unlocked by she who would assist the Hero of Winds in his fight against Ganondorf. Tetra was the descendant of Zelda who did that, and once Ganondorf was dead, the part of her that was Zelda was forgotten.
I can see that being true, I don't know a ton about Wind Waker myself though. I've heard the same thing about Zelda and Shiek too, so it seems to be an ongoing theme for Zelda.