Do lenses render color differently? They sure do!
Zeiss 35mm f/2.0 Distagon T* ZF.2 @ f/5.6, SB900 flash bounced off near wall to the right.
Nikon 16-35mm f/4N VR, 35mm @ f/5.6, SB900 flash bounced off near wall to the right.
I notice no discernible difference in sharpness here. The Zeiss has a bit better bokeh, but that’s subjective anyway. No, the biggest difference I see is the color. Both look fine by themselves, but compared side-by-side, the Zeiss renders a bit cool and the Nikon a bit warm. Which is better? Again, that’s subjective, and probably changes by subject.
The glass in a lens can influence the color of the image. This includes when shooting raw in a digital camera – it’s affecting the light that the sensor receives. Is this a deal-breaker for one lens over another? Probably not, unless you’re shooting fine-art landscapes or high-fashion portraits in JPG. It is, however, information that any discerning photographer should be aware of. If you want to get a print of your image, and have it look exactly like you saw it, you should know how your lens affects the rendering of that image.