What is the difference between a closed shop and a lockout

A closed shop refers to business which employs union workers alone, whereas in case of a lockout, such a business does not permit employment of union workers.

Lockout serves as a mean to curb labor union demands. In lockouts, the owners of such businesses lock out or block the entry/employment of union workers.

In case of a closed shop, all the employees represent members of labor union. The two concepts represent exactly opposite scenarios.