There is a woman in a white tank top and camouflage pants with a big black belt on a stage holding a microphone.
A woman is on stage holding a microphone.
"woman in a white tank top and camouflage pants with a big black belt on a stage holding a microphone." is a rephrasing of " woman is on stage holding a microphone"
White tank top and camouflage pants further describes what the woman on stage is wearing.
A woman on stage refers to woman in a white tank top and camouflage pants with a big black belt on a stage as part of the total description holding a microphone.