If you are interested in getting better at identifying bumble bees, I highly recommend the book titled Bumble Bees of North America (Williams et al., 2014, Princeton University Press).
Additionally, try out this website, produced by Michael Warriner (if you are interested in Texas bees you have surely heard of this wonderful man!). And the following diagram summarizes that page. Note that these are guides to the FEMALE bumbles of Texas.
Finally, here are some photos that show details of various common bumble bees in Texas.
Female B. sonorus. (Photo courtesy of Tom Fisher)
Male (foreground) and female B. pensylvanicus. This male is often misidentified as B. fervidus. (Photo by J. Beckham)
Easter carpenter bee (Xylocopa virginica)- NOT A BUMBLE! Note the shiny, almost hairless abdomen. (Photo by J. Beckham)