The Great Sunflower Project

Bumble bees (Bombus spp.)

Photo by Rich Hatfield
Have larger, stockier bodies than honey bees
Are yellow and black (though some have red or white) and hairy.
Their abdomens are hairy unlike a carpenter bee.
Pollen is carried as moist pellets on the expanded hind legs (corbiculae)
Females can sting more than once
Are un-aggressive unless you appear to be attacking their nest

Carpenter Bees (Xylocopa spp.)

by Ginny Stibolt
Are large and robust and resemble the bumble bee
Are often but not always totally black in color
The top of the abdomen is shiny not hairy like a bumble bee. See in the picture.
Have strong mandibles that they use to dig into wood where they establish nests
Are not likely to sting unless handled
Females can sting more than once
Have a surprisingly mild sting

To tell the difference between bumble bees and carpenter bees, watch how they move. Bumble bees fly low to the ground and move slowly. Carpenter bees hover motionless at eye level or along wooden beams and are rather quick. In addition, try to see the top of the carpenter bee's abdomen it is practically bald and appears to be entirely black and rather shiny. Bumble bee females carry their pollen as moist pellets on the expanded hind legs (corbiculae), like a honey bee, and unlike any of our other bees. Also, the Carpenter bees splay their wings while landed (Bumble bees fold them neatly over the back).

Honey bees (Apis mellifera)

Very dark Honey bee. Photo by Ron Hemberger
Are about the length of the nail on your thumb (an inch)
Have gold to dark brown or black shiny abdomens with subtle stripes
While they have hair, the hairs are sparse.
Have hairy eyes
Females sting once and then die
Are found year round
Are not native to the US
Carry pollen on their hind legs

Green metallic bees

Photo by Ron Hemberger
There are a couple different genera with bright green bees - Agapostemen, Augochlora, Augochlorella, and Osmia....