Do they have the intent (legal or not) to stay permanently?
An immigrant has an intent to settle, an expat doesn't. In America, one could theoretically lose work authorization should he refer or present himself as an immigrant (if he or she is on a legal status that doesn't allow for immigrant intent).
Same thing in Europe. Thousands of EU citizens live and work anywhere in the EU outside their home country but have no intent on permanently staying there. Often for decades. They are very much expats.
An immigrant has an intent to settle, an expat doesn't. In America, one could theoretically lose work authorization should he refer or present himself as an immigrant (if he or she is on a legal status that doesn't allow for immigrant intent).
Same thing in Europe. Thousands of EU citizens live and work anywhere in the EU outside their home country but have no intent on permanently staying there. Often for decades. They are very much expats.