Student or Learner
Which is the difference between "in a hospital" and " at the hospital"?
Hi and welcome to Using English.
The general difference between "in" a place and "at" a place is that the first is inside the building and the second is somewhere in or around it.
However, for the hospital (compared to a restaurant or theater, for example), if you say "in" it sounds as though the person is a patient, while "at" sounds like you are visiting.
Context could change that meaning, though.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.