I'm about or going to

Hello, is there any differences between "going to" and "about" below is some examples.
I'm about to kick your ass. I'm going to kick your ass.

(Not a Teacher)

The first one is a threat. The second is a statement of intent.

They're sometimes fairly interchangeable, and often not at all. A child who says 'I'm going to be an engine-driver when I grow up' isn't 'about to be an engine-driver'.

b