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.
Technically yes. The legal term for someone on temporary work authorization without an intent to immigrate would be something like "non-immigrant alien resident". The common term would be... expat.
The common term, yes. But the legal definition of expat is:
2) Expatriate The term “expatriate” means— (A) any United States citizen who relinquishes his citizenship, and (B) any long-term resident of the United States who ceases to be a lawful permanent resident of the United States (within the meaning of section 7701(b)(6) ).
That's what I've read, too, i.e. intent to settle, or not.
Maybe wanting to move forever (i.e. migrant) is more common, if one is from a poorer country, which could explain why some others here thought that "immigrant" implied "poor and less educated".
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.