The difference is FetLife is 90%+ sex.
Tumblr has sex, memes, libraries posting cute pictures from old books, cat gifs and everything else.
Tumblr has sex, memes, libraries posting cute pictures from old books, cat gifs and everything else.
I think you'd be surprised at the amount of people who are on Fetlife and aren't looking for sex but rather enjoy the kink community, are photographers, or content creators of other types (the blogging feature for example gives you the option of treating/tagging posts as blogs or as "erotic fiction", catering towards that particular wing of the sexually creative types).
Hence my statement of (plus other features, granted) in the original comment.
Sure, it's oriented towards the Kink crowd but Kink != explicit sex.