Why the Confusion?
'His' and 'He's' have similar pronunciation:
However, they have totally different spellings and meanings.
Main Similarity and Difference
'His' is the possessive form of 'he' and it shows something belonging to a male person (i.e. a man or boy). 'His' can either be a possessive determiner or a possessive pronoun.
Here, 'his' is followed by another noun 'girlfriend'. Therefore, it is a determiner.
Here, 'his' stands alone. Therefore, it is a possessive pronoun.
"He's" is a short form of subject pronoun 'he' and the third person forms of the verb 'be' and 'have':
- He's → He is
- He's → He has
He's = He was?
Although you might hear someone use the contracted form of 'was' in spoken language, but you should know that it is not grammatically correct. Unless there are obvious signs that the sentence is in the past tense, avoid using 's' as a contracted form of 'was'.