Speed and memory
In our performance index the GeForce RTX 3060 scores 24 and the Radeon RX 6600 scores 22, which makes the GeForce RTX 3060 about 9% faster. That is a small gap, below what most people notice without a frame counter.
The GeForce RTX 3060 has 12 GB of video memory and the Radeon RX 6600 has 8 GB. That difference matters at 1440p and in new games at High textures, and it can outweigh a small speed advantage as the card ages.
In our estimates for popular games at 1080p on High, the biggest gap is in Call of Duty (60 against 55 fps), and the smallest is in Red Dead Redemption 2 (84 against 78 fps). Games that are light enough to run above 200 fps on both cards show little difference at all.