HSA and MSA a very similar in plan design. One of the major differences is, MSAs are only available to self-employed and small employers (50 employees or less)

In addition:

• With HSAs, contribution amounts have been increased to 100% of the deductible (From 65% single, 75% family - MSA)
• Both employer and employees can contribute to an HSA in the same calendar year
• Some qualified plans may have a first-dollar benefit or low-deductible benefit for preventive care only
• More people qualify - individuals need NOT be self-employed, and groups over 50 are now eligible to participate
• "Catch-up" contributions have been established
• There is no limit on the number of accounts that can be established
• HSAs are a permanent feature of the Tax Code