Translation:The tall trees are next to the hotel.
I don't think there is much difference. Beside would work in most of the same instances. But on the other hand I have next door neighbors or live next to my neighbor, but to say beside would not be used at all in the first case, and in the second it would imply closer living quarters.
Do I understand correctly that the subject of this sentence is "a szálloda" and the object (in Accusative case) is "a fák"? If this is the case, why are the subject and object switched in English? Or rather: How can the subject (in Hungarian) be declined and be in accusative?
Yeah, it could be. Hungarians do not really learn these things (including the various suffixes) as "cases". At least last time I checked it was not so. It is more like trying to fit a bunch of square pegs into one round hole. :) Matching the Hungarian system into a terminology that fits a whole big family of other languages.