Final answer:
U.S. citizens employed abroad by U.S. companies are known as expatriates, which is distinct from host-country nationals, third-country nationals, and inpatriates.
Step-by-step explanation:
U.S. citizens employed in U.S. companies with work assignments outside the United States are better known as expatriates. An expatriate, often shortened to expat, is an individual living and working in a country other than their country of citizenship, often temporarily and for work reasons. This is in contrast to host-country nationals, who are employees from the country where the subsidiary is located; third-country nationals, who are employees from a country other than the parent or subsidiary countries; and inpatriates, who are employees from a foreign country working in the parent company's country.