I wish router manufactures didn't do this. TPLINK is even worse than asus about keeping the name the same and changing the part numbers.
Asus has 3 different models the RT-ax3000, GS-ax3000, rt-ax58u which all appear to be the same they use exactly the same parts and have the same fccid. The GS one is their so called "gamer" router they charge more for because it has fancy leds I think.
In addition there are now "V2" models of all those routers. These have a new FCC number from 2022. The main difference appears to be it now has a 2.5g WAN port...along with a higher price tag. They might also use a different/newer broadcom radio on the 5G band but it is unclear the hardware wiki thing I search you can't 100% trust.
This is one of those things you many times need to see the actual box...especially with the tplink models. Most online retailers do not clearly tell you the hardware revision.
The asus one should be a bit easier since it has a 2.5g port so you can tell the newer model.
The performance though will be pretty much exactly the same when they use the same wifi chips. Asus is better than most at getting firmware updates so you can download the latest software. The actual firmware that runs in the radio chips comes from broadcom and is the same even between different brands.