What's the difference between: उसे सलाद पसंद नहीं है and उसे सलाद नहीं पसंद है
No difference your sense
Why is it उसे and not उसके?
Because we're talking about what she likes, not what her salad likes.
उसे is equivalent to उस को, i.e. to her, not her possession.
Why "use" and not "vaha"?
The literal translation of the sentence is something close to 'To her, salad is not liked' because Hindi does not have a single verb for 'like'. उसे is 'to her'.
पसंद isn't a verb, so you can't say 'vah salad nehin pasandi' or something, if that's what you were imagining.
It's an adjective, so you have to describe the salad, as it is to her. That 'to her' gives you उसे.
Huh, but I really like salad tho
I wrote उसको सलाद पसंद नहीं है and it was rejected. उसको is exactly the same as उसे so is there any reason for this?
Salad is not liked "by her"