This primarily accounts for the Norco having the lowest price. And it takes up quite a bit less shop space in your garage. A downside to the shorter chassis is - If you tend to always be lifting your vehicle from, say, the back pumpkin, the other model is a little bit easier to roll under, set and pump because of the longer length. The Norco uses a single pumping piston with a foot pump to help raise the lift arm to the load quickly. The Milwaukee uses two pump pistons to move things along quicker.
All systems seem to work fine with no real stand out differences.
All models feature a 45 degree to horizontal pumping arc - Convenient for lifting while deep under the vehicle. Both use a welded on caster shoulder with replaceable metal casters, Milwaukee uses a roll pin to keep theirs in place in their cast iron holder while Norco's snap-ring through formed steel. The Milwaukee is warranteed for one year while the Norco has a lifetime warranty against defects in parts and workmanship. Also, Both companies have several service centers across the country. That wasn't so hard.