Hello Vera,
You should consider different colour foods as the same as the original food but extra in one or 2 things, meaning orange cauliflower is the same as white cauliflower but with extra yellow colour which is vitamin A.
For nutritional value I suggest this site:
Nutrition Facts and Analysis for Cauliflower, raw
As for what the orange/yellow cauliflower has more of, this is a reliable source:
Vitamin A rich cauliflower hits the shelves
By the way, beta-carotene is a yellow/orange pigment that is converted to vitamin A in our bodies. To aid at absorbing the beta-carotene, I suggest you consume your cauliflower with added olive oil (of vegetable) because the pigment dissolves in fat/oil not in water.
Luc H.