No. It is similar but illegal alien is not a technical term it’s the popularly used jargon, nowhere found in the U.S. immigration laws. Moreover, undocumented are those who entered with a visa but overstayed and those that entered without permission. Whereas, illegal is just those who entered the U.S. without being inspected and admitted at a port of entry. Because of its insulting connotations even though it covers a wide variety of types of people, at Andres Mejer Law we use the more accurrate term, undocumented immigrant.