a laborer is a worker with hard physical job. a worker can be a laborer too, for example factory workers. the term worker is just a very broad definition comparing with the term laborer.

It's hard to say without more context, but laborer often refers to a person who does a very physical job that involves heavy lifting or building something. A worker usually refers to someone who works in an office.

a person doing any work, you can call him or her a worker; but if you call a person laborer, his or her work must need physical strength.