Floor jacks - MAC Tools 2.5 ton vs Craftsman 3 ton

I've had the Craftsman 3 ton floor jack pictured on the left for 19 years. It's always worked fine, raised anything I needed it to raise. However, I've never liked how the handle isn't fixed to the jack. It's always a pain in the neck to keep it inserted, so I went on the hunt for a more traditional jack with a fixed handle.
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I found the MAC Tools 2-1/2 ton jack, and right away I noticed the obvious size difference. Now, engineers aren't stupid, so I know some thought went into each design. My question for the experts is, do they determine the lifting capacity simply by what the actual hydraulic mechanism is rated for, or is there also the factor of the design of the jack? The MAC Tools jack looks more stout and stable, but I guess if the hydraulic part can only lift so much, it's a moot point.

Am I wasting brain energy trying to figure this out? Ah screw it, I'm gonna go have a beer...