in MA can workers compensation payment be considered as severance pay

In Massachusetts there is no requirement to pay severance pay by an employer, absent a contract or union bargain to the contrary. With that said, an employer could restrict or limit a non-contractual severance for any (or no) reason at all. If you have a contractual right to severance then you should read the small print in your contract to see if there is a specific clause, otherwise it should not be considered part of your severance as it payment for an injury.

Workers Compensation is not something that is part of your severance package. You are only entitled to severance if it is part of your contract. If you have a workers compensation attorney you should contact him or her to discuss the matter. Often, when people get severely injured on the job (or sometimes not so severely) a lump sum workers compensation package is given to cover future wages, although it may feel like severance it is different.

No. Things get dicey in Mass workers' compensation if a settlement is coupled with an agreement to tender a resignation. Your question is touching on this issue, i.e the coupling of the discussion of resignation with settlement. They are separate entities entirely and stiff penalties are imposed if there is an attempt to persuade a claimant to resign from a job in exchange for a settlement. Severance is severance related to the policies of the employer, WC is state regulated and unrelated.