Labour supply: It refers to the number of persons willing to work at different wage rates. It depends upon the existing wage rate and is measured in terms of man-days.
Labour force: It refers to the number of persons actually working or willing to work. It does not depend upon the wage rate and is measured in terms of number of days.
Workforce: It refers to the number of persons actually working. This measure does not include those persons who are willing to work but are not getting work.