Can an employer give some employees severance pay and not others?

My husband is being terminated from his position with a company he has worked 28 years for. The entire shop is being terminated and they are outsourcing the work to another company that they have talked with to employ these guys. They have let several others from different parts of the company go recently and they were given a severance package. The company says they feel in working with this other company to provide these guys employment (keeping their experienced guys doing the work for them but getting paid thru another employer) they do not owe them a severance package - the job is their package. Can they do that if they have given severance packages to others they have terminated in the last month? And these guys still have to fill out an application, pass all their required tests, etc. before they do hire them.