You seem to have the right insect ID; descriptions are invariably black, but since these bees chew wood, perhaps the brown one had a dusting on it, or even pollen.

I, also, thought that it might be covered with a very fine dusting of pollen, but I was able to observe it closely at work at eye level, and studied it thoroughly. It was the color of coffee with milk, evenly colored throughout, including the legs and wings. There was no evidence of pollen on the hairs, and they were the same color down to the base. (These bees don't enter the flowers, they just drill through the base.)Perplexing.
Diana

Around here, the male carpenter bees are brown.

Here is a link that might be useful: Carpenter bees

Cindy - I was finally able to get the site you sent me - http://www.lawestvector.org/carpenter_bee.htm
Your California male looks much more colorful than mine - mine looks just like light coffee. I will research to see if there is a comparable male in south Texas.
Diana

Cindy C, thanks for the info. I have often wondered why the diff. colors. Peg