As far as basic design is concerned, both are conversions of the Number 4 Rifle to Number 4 Mark 2 specs. This involved hanging the trigger from the frame of the rifle (what the designers call the 'body') rather than hanging it on the triggerguard. Once this conversion is done, the rifle's trigger pull will not change, should you have to take the rifle apart. This is viewed by many as an improvement on the basic design.
Either rifle is factory-sighted for a 174-grain bullet at 2440 ft/sec MV. If you use 180-grain sporting loads, your iron sights should be dead on. If you shoot the must faster 150-grain loads, the rifle will shoot a bit high, but it is not hard to adjust yourself for.
The old .303 cartridge has taken every species of big game in the world. It is well-suited to take anything in North America, with the single possible exception being Grizzly, for which I would want something about the size of an 88. But that's me.
Enjoy, have fun!