on the verge of and to be about to

[Majid72]

Hello
would you please tell me what's the difference between "on the verge of and to be about to"? Can they be interchangeably used in all contexts?

Thanks a lot

[Kitosdad]

Only if you were to be able to imagine all of the possible contexts.

Yes and No is the reply, but 90% YES would be my thought.
_________________
If you need me, I'm here.

[Majid72]

Could someone please tell me some sentences in which the two words cannot interchangeably be used?
I think there are sentences which follow the above rule. for example,take the two sentences:

-I'm on the verge of eating my lunch.
-I'm about to have my lunch.

I believe the second is better than the first.

Regards.