Non-Massachusetts
portion of income would refer to income that did not come from a
Massachusetts source. For example,
income earned from another state such as working in another state or having a
rental property in another state.
Income earned while
not a resident refers to any income from any source that was earned while
you did not live in a state (such as Massachusetts). For example, if the question was asked in the
context of “income earned while not a resident of Massachusetts,” it could
include income earned from working in Massachusetts while living in a different
state.