Conscience vs. Conscious

Your conscience is your sense of morality, the “voice in your head” that tells you that you shouldn’t, for example, throw rotten eggs at your English tutor’s car. The adjective form of conscience is conscientious, which means “showing great care and thoroughness”:

obey the dictates of your conscience
a conscientious worker

Conscious is an adjective meaning “awake” or “aware.” Its noun form is consciousness:

felt self-conscious in front of a crowd
regained consciousness