Honey caps are just wax. Brood caps are have to breath so they are a mixture of wax and other things. When a hive is just getting established and has no cocoons to use, they use pollen to mix with the wax. When the hive is established they use chewed out cocoons to mix with the wax. The pollen/wax mixture is usually yellow. The cocoon/wax mixture is brown. As far as honey caps, when they first cap it it the wax tends to be white, but how white it appears depends on the genetics of the bees. Some leave a little air so the caps look very white. Some fill the cell right up to and touching the cap and they look "wet" and the color of the honey instead of white. When wax is first made it is white. After the bees have time, they paint it with some secretion from their mouth that makes it more yellow and much tougher.