I'm not sure if they are the same camera hardware, but I think they are different. iMac Tech Specs page says: "1080p FaceTime HD camera" and ASD lists "12MP Ultra Wide camera with 122° field of view", ƒ/2.4 aperture and Center Stage.
The iMac doesn't support Center Stage. I think CS and the Ultra Wide camera, are contributing to some of the issues as they are taking that 12MP ultra wide image and cropping the image...maybe down to 720p?
I'm hopeful that they can fix the other image quality issues -- poor dynamic range, wonky skin tones, flat image, etc. as that can be adjusted a bit by software. But this decision to use the ultra wide and Center Stage...personally I think it's a mistake. I'd guess that 90% of the time the ASD camera would be used by one person sitting fairly static, but that's just my opinion.