[mytailorisrich]

A strikebreaker is usually someone external hired specifically to replace a striking worker. That's why this may or may not be restricted by law.

Very often a 'scab' (which, again, is an insult) is simply an existing worker who's decided not to srike and who constinues to work as usual. Though the term may also refer to a strikebreaker.

Anyway, it's similar.