Question about Le Creuset Signature

I have Le Creuset products in different colours. In my experience there is no difference between different colours, certain colours are just more expensive (because special edition etc...) I don't know exactly why... with the roasters there are 2 features that can differ (besides the colour): Coating inside (enamelled/non-enamelled) and lid knob (metal or plastic). However, the description indicates this.