What Is Their Main Difference?
We use 'has' for third-person singular nouns or pronouns. Look at the examples below:
'Have' comes with both first-person and second-person singular pronouns or nouns, along with all plural nouns and pronouns. Look at the examples below:
I'm really sorry, but I
Both are conjugations of the verb 'have'. Look below:
The closet seems full but I still fell I
Are They Interchangeable?
Since they differ grammatically, they cannot be used interchangeably. Compare:
✓ I always
X I always
As you can see, this example is incorrect.