1) The workers, who went on strike, were dismissed.] All the workers were dismissed. Additional info: they went on strike. But the reader is likely to infer that the cause of the dismissal was the fact that they went on strike.
2) The workers who went on strike were dismissed. ] Only the striking workers were dismissed. (There may be other workers.)
3) The workers, who wear pink socks, were dismissed. ] All the workers wear pink socks. All were dismissed. The two facts are not necessarily related.
4) The workers who wear pink socks were dismissed. ] Only those who wear pink socks were dismissed. It seems likely that there was a connection; but it might be a coincidence.
5)They have two children who are still at school.] They might have more than two children.
6)They have two children, who are still at school. ] They only have two children.