The Revell Mk.6 kit has its origins with Hasegawa. The kit has wing slats, but they can not be deployed in the extended position, which was normal on the ground.
Basically the (Canadair) Mk.5 lacked slats but had wing fences, and the Mk.6 had slats, no wing fences. There were possibly differences in some small intakes and access panels on the fuselage, due to the different engine in the Canadian aircraft, but these may not be noticeable - further research would be needed.
I'm not entirely sure, but I
think the Canadian versions (also used by RAF and Luftwaffe) had a wider rear fuselage, due to the engine change. If this is the case, then as far as I know,
none of the available 1/48th scale kits have this, although the Airfix kit
might have. Again, the difference would probably not be noticeable. (Airfix kit also released as a USAF version, so likely no difference in kit parts).
A good alternative kit would be the Academy kit, in the "Mig Killer" boxing, which is equivalent to a Mk.5, with wing fences, no slats, and nicely detailed. I believe the other Academy kit is an earlier release originally under the Minicraft label, not as detailed, and some inaccuracies.
EDIT :- Did a bit of digging, and it appears that the fuselage width is the same, with only the internal dimensions being increased to accommodate the new engine (it was the Aussie CAC Sabres that were wider !).
Pic of the box art below showing which Academy kit to go for, often on e-bay and elsewhere at very reasonable prices, or around £22 new in the UK.
Most reviews state it's the best Sabre kit in 1/48th, although Airfix may now have a slight edge with their newer kit.
I built one around 18 years ago, and was pleased with it (pics below in USAF colours from kit decals).