The original question was "Do you sing differently when you sing a lead in a choir?"

I suppose "a lead" is a person singing alone or singing a main part while others do inconspicuous backup. If so, a lead does sing differently - louder, more forcefully, perhaps with improvisation and special effects.

A person in the choir, on the other hand, is supposed to blend. Blending is hard to define, but when it's not done, the choir sounds ragged and amateurish. A choir consisting of people who are all singing like leaders is awful to listen to.

My explanation of blending is this: Let your voices cuddle.