"I enter the hospital."
Hairi はいり and iri いり are both readings of 入り。tried to find a good rule for when to use each and found this. https://www.lingq.com/forum/learning-japanese-forum-ask-a-tutor/iru-or-hairu/
I think that the person is outside yet, because s/he says 'I enter the hospital'.
The image of imagination is 'to' or 'toward' the hospital.
わたしは病院を出ます。 I leave the hospital. (sorry, please offer more better English sentence)
This person is in the hospital. I think the image is 'from' the hospital.
And the particles are different as the same the meaning of each English sentences.
(i'm on mobile ) 入ります is separeted into 入り and ます and as a consequence is pronounced いります which is incorrect , the correct pronunciation is はいります