Whilst I want to say yes, it depends on how they will be used. If they are going to be resized to 800px for a website then probably not, printing an 8x10 side by side might be better to compare. Like I said in my first post it's how you use it, and to an extent what lens you are using.
Taken from a forum discussing 400d vs 550s vs 7d:
1. Don't buy a new body for image quality (anything above 8-10 Mega pixels is fine) unless you are looking for high ISO quality.
I just sold a 400D for a 550D, I don't really see any image quality difference the 400D took great photos. I do have more ISO performance, can crop in on photos without losing quality,.. but really the video is the big thing for me that and the LCD is much better!
Think of a new body as new features (faster focus, higher ISO, faster shooting) but not better image quality. That being said if you like to blow up your prints to a HUGE poster size then higher Megapixel will help.
2 .I agree with others... it's all about the glass and how the camera is set up... understanding light has a lot to do with it too... and maybe he done some post processing... do you shoot RAW
lots of reasons his photos may look better but there really isn't that much difference in the 2 bodies...