Well if you are running around in a CVR(t) then either of them are going to cause you trouble!
On the other hand the Firefly is going to be impervious to the 30mm Rarden gun on the Scimitar - although Scimitars did kill a T62 in the Gulf? So possibly not? The 76mm HESH from the scorpion should cause it issues.
The AML-90 on the other hand is a light armored car with a big gun.
30mm Rarden will kill it.
I would also note that the only example I could find of CVR(t) being damaged by a tank gun was one hit by an Iraqi T55 with the Sabot round passing right through the light tank without injuring the crew.
CVR(T) - the little tank that could
We shall never known for sure (and I'm glad for the British crews).
The Firefly is not going to last too long in front of those small killers, that's for sure. The AML-90 even less, even if, as with the FV family, you have to hit it, first.