Janet & others wrote:
cropping back bushes and scrub etc? - will a chain saw TRIM a hedge?

No. It's likely to snarl up and take your face off.

Rubbish
Alarmism
Whilst there are some circumstances, while dealing incorrectly with
real timber, that kickback could do a facial injury, "take your face
off" is an emotive and unlikely (seriously incompetent like not
noticing a tree) result of hedge trimming.

If , to make a sale, he implied a hedgetrimmer and chainsaw are
interchangeable tools for your job, then congratulations. You've had a
narrow escape. Without having made an expensive mistake, you have
identified someone who does not know his stock, does not care for your
safety, knows damn all about garden maintenance, and even less about
machine maintenance. Don't do business with him; find someone else.

In this regard I do agree with you.