The Leather Pride Flag is a symbol for the leather community, which encompasses those who are into leather, Levi's, sado-masochism, bondage and domination, uniform, cowboys, rubber, and other fetishes. Reportedly, gay leather aficionados might also modify a rainbow flag to have a black stripe instead of a violet one.
Bears also tend to be older, and perhaps larger or chubby.
There does not seem to be one single symbol that represents bears in general. Rather, there are many symbols that have been adopted by local clubs, bars, and other bear groups. The Bear Pride Flag shown below is from Spags, a Seattle bear bar. The colors of the flag represent the earth and the various bears that live between the sky and the ground. The golden yellow paw shaped sun represents the spirit and brotherhood of bears all over the world.