At or In
 

I am IN the hospital. Estoy en el hospital.
Un paciente en el hospital.

I am AT the hospital. Estoy en el hospital.
Actualmente ubicado en el hospital.
Actualmente se encuentra en el hospital.

¿Sin más contexto qué significa el oración "Estoy en el hospital"?


Otra ejemplo:
Mi esposa, una hillbilly de Kentucky, diría que "my shoes are IN the floor" en lugar de "my shoes or on the floor". Creo que "IN the floor" es un inglés antiguo y arcaico, pero no estoy seguro.

Como siempre, gracias. Bob Ritter, Pensacola Florida.

I would call this regional usage.
On and in are usually not used interchangeably in English and have been separate words in the language since its inception.
The Spanish phrase "en el hospital" can mean "in the hospital" or "at the hospital," which both mean the same thing in American English (one's location), but if you're a patient at the hospital, we usually make it clear that we're not there visiting someone by providing more information (if there's any confusion).
The British use "in hospital" to mean that you're a patient, and "at hospital" to mean you're visiting someone in the hospital.

Thanks Rusty.