It's hard to see in the pics, but I know what you're on about.
Different materials respond different to anodizing, and the amount of polishing they had before being anodized can also have an effect on colour and shine.
Being the same brand, your parts should (IMO) have the same exact colour and shininess.
Are these parts from the same era? If the seat clamp is a lot younger than the headset, that could explain a thing or two.