As far as i am aware, they are exactly the same kits. Over here in Europe, we get the Revell kits in the blue box, i think cars may be grey,and armour is black, i assume this is what you saw.
Someone did once explain the relationship between the two companies, but i can't remember what it is off the top of my head.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3