Kal-L started out with a pretty simple suite of abilities. Faster than a train, immensely strong, durable against anything short of high explosive military ordinance, and able to leap great distances. The text also implied his mental abilities were on par with his physical traits, but that was rarely shown, and he could reconfigure his face (although they dropped that one very early on). That, however, was it. By the mid-Silver Age, Kal-el was shoving planets around and immune to any harm other than kryptonite or magic.
Contrast that with Wonder Woman. Diana started out at roughly Kal-L's power level (although she relied on her bracelets rather than being invulnerable), and her abilities grew over the years, but not to the extent that Superman did.
One of the factors I can see contributing to the difference is that Wonder Woman wasn't competing with a feminine analog of Captain Marvel.
Yes, there were other strong guys out there in comics (one actually called Strong Man), but none that rivaled Superman at the cash register. Hard as it is for us to believe today, the Captain not only matched but surpassed the Man of Tomorrow's sales. Almost from CM's first appearance it seems like an arms-race began between National Periodicals and Fawcett Publications to make their hero the mightier of the two. There was no character out there to impose that threat on Wonder Woman, or Batman, or any of the other of (what would become) DC's stable of best sellers.
At the same time, there was power creep. Green Lantern gained a wider array of abilities as time passed, although it included a trade off with a few of the feats he showed early on. The Atom went from an uncommonly strong midget-wrestler to a guy able to stop trains and use bulldozer blades for a shovel with his bare hands. Still none of them were even close to what Superman experienced in change of ability, but none of them had a sales adversary threatening their place in the market.
So, if there had been no Captain Marvel, what would Superman look like today?