This item Canon EOS R5 Full-Frame Mirrorless Camera - 8K Video, 45 Megapixel Full-Frame CMOS Sensor, DIGIC X Image Processor, Up to 12 fps Mechanical Shutter (Body Only) Canon EOS R6 Full-Frame Mirrorless Camera with 4K Video, Full-Frame CMOS Senor, DIGIC X Image Processor, Dual UHS-II SD Memory Card Slots, and Up to 12 fps with Mechnical
The R6 II adds just 4MP to the resolution of the R6 but that brings it back up to the baseline 'norm' for a full frame camera. (Image credit: Canon) • Canon EOS R6 II: 24.1 full frame CMOS, up to ISO 102,400 • Canon EOS R6: 20.1 full frame CMOS, up to ISO 102,400. So the key difference here is the increase in resolution from 20MP to 24MP.
A full-frame sensor is equivalent to traditional 35mm film and larger than APS-C sensors. Full-frame camera users experience no cropping on their images, so they’re called full-frame sensors. They capture the entire frame. The larger sensor size means full-frame cameras are generally larger and heavier than APS-C cameras.