An L-2 spouse is employment-authorized incident to status and needs no separate application to work, which is the sharpest practical difference between L and TN. An unmarried child under twenty-one may live and study in L-2 status, but that eligibility ends on the twenty-first birthday.
Two dependants, two very different timelines
Hypothetical example: the Ouellette household leaves East Ferris on an L-1A transfer with a spouse who intends to return to nursing and a daughter who turns twenty-one fourteen months into the assignment. The spouse's position is comparatively simple, since employment authorization is incident to L-2 status; her practical obstacle is professional licensing in the state, not immigration permission. The daughter's position is a deadline.
L-2 dependent eligibility ends at twenty-one, and a birthday is not a change of circumstances anyone can appeal. If she intends to remain in the United States afterwards, the alternative has to be arranged in advance, most often a student route with its own admission, funding and documentation requirements and its own lead time. Households routinely discover this at the extension stage instead.
Map both dates, the twenty-first birthday and the seven-year L-1A ceiling, against the assignment before anyone signs a lease.