https://en.wikipedia.org/wiki/GM_8L90_transmission
An easy way to tell the difference in gearing between the two.
Find a 8 speed GM and drive it around a bit in 6th gear which is 1-1. Do the same with a Tundra in 4th gear which is 1-1. You should feel the difference in gearing, especially if you try and run over 70 MPH.
Somewhere Toyota electronically softened the gas pedal on the Tundra. I found that out after a guy that had an 07 Tundra drove my 15 Tundra and noted how different they felt tho they had the same engine, transmission, and rear end ratio. Companies like Pedal Commander sell software to wake up your gas pedal. I have never found the need with the Tundra. Those and other tuners are popular with the Silverado. Rear end ratios just don't make up the differences in driving with all the under and overdrives. Like I said, your best bet is going to drive all you're interested in and buying the one that makes ya smile.
The next gen Tundra is rumored to get a turbocharged V6 like the Eco Boost. Hope they keep a reliable V8 option.