It’s not a British/American thing - any nationality can be referred to as an expat. It’s all a matter of what you’re trying to emphasize. The term “expat” implies being in a different country and feeling like a foreigner - using the term suggests that there is a degree of culture shock or not feeling like you fully fit in. Foreigners will often look for expat communities for support. That may be why you’re noticing it with British and American foreigners - you can be a French expat or a German expat or any other nationality, but if English isn’t your first language you’re less likely to know the term.

You’re also less likely to hear an American or British person refer to people who come to the U.S. or U.K. as “expats” - the term "expat"implies inclusivity with other people who came from the same place, while “immigrant” carries the implication of someone from a different culture that came here. As a native English speaker, I would think it sounds perfectly natural to hear someone say “I’m a Syrian expat”, but I would only use the term to describe “the Syrian expat community” (i.e. the Syrians that have come here and are relying on each other for support). If I were describing the same person, I would say “Syrian immigrant” because I’m not the one feeling the culture shock of being in a foreign land. (or I would use the term “refugee” which carries the implication that they’re here, but not by choice - they were forced out of their home)

“Immigrant” often also implies some sort of formal legal status, although in a looser sense it just means that you live in that country on a permanent basis. All immigrants are also expats, but not all expats are immigrants.

As others have pointed out here, while neither term is by itself positive or negative, “expat” will almost never be used in a negative sense, but “immigrant” can be used in a derogatory way, although it can also be neutral or positive depending on the speaker and context.

In theory, An expat is someone sent abroad on short/mid-term mission while working for an employer, while a migrant is someone moving abroad to find a job and sometimes to start a new life.

This means that, if let’s say if a Mining company in Ghana sends someone to New-York to be the “US sales director” that person would be an an expat While an American opening an hotel in Ghana would be an immigrant.

But indeed, in many cases : Expat = European/North-American, Immigrant = From somewhere else

Because “immigrant bad” and they don’t see themselves as bad.

cause usually its not permanent, like with immigrants.

A quick Google search says that an expat usually only lives in a new place for a limited period of time. An immigrant moves to a new place with intent to settle.

Whether that’s how it’s used colloquially is another matter…

I’ve always considered an expat to be different from immigrant in that it’s temporary.

I lived abroad from 2009 to 2011, simply because I could, as my employer had to fly me in to work anyway - It didn’t matter to me whether my home airport was TRD or PRG. I was chatting with someone local, and when I told them about my situation they’re actually the ones who used the word expat. Personally I considered myself a long term tourist.

The etymology might help break down some of the nuance here

According to etymonline the etymology for expatriate (often shortened to expat) is:

“to banish, send out of one’s native country,” 1768, modeled on French expatrier “banish” (14c.), from ex- “out of” (see ex-) + patrie “native land,” from Latin patria “one’s native country,” from pater (genitive patris) “father” (see father (n.); also compare patriot). Related: Expatriated; expatriating. The noun is by 1818, “one who has been banished;” main modern sense of “one who chooses to live abroad” is by 1902.

Immigrate, is similar, but is more used to describe moving to a place:

“to pass into a place as a new inhabitant or resident,” especially “to move to a country where one is not a native, for the purpose of settling permanently there,” 1620s, from Latin immigratus, past participle of immigrare “to remove, go into, move in,” from assimilated form of in- “into, in, on, upon” (from PIE root *en “in”) + migrare “to move” (see migration). Related: Immigrated; immigrating.

The closer synonym to expatriate would probably be emigrate, the opposite of immigrate, to leave a place.

As to why one might use expatriate over emigrate; consider the sentence “I’m an American immigrant”. It’s kind of unclear if you’re trying to say that you are an American that has migrated to another country (as in “I’m an American immigrant living in Brussels”*), or someone who has migrated to America (as in “I’m an American immigrant from Slovakia”). Using expatriate removes the ambiguity: “I’m an American expatriate” and makes it clear that the speaker is trying to convey where they are from.

* technically, using emigrant here would be more clear, but English is a lawless and lazy language

Why Brits and Americans? Every major city has expats.

You go abroad for a job, usually temporarily -> expat

You give up your citizenship to move to another country -> immigrant

I always assumed it was simply a matter of perspective. E.g. someone leaving the USA for the UK is an expat to the USA but an immigrant to the UK.

Immigration is permanent residence. You can move somewhere not permanently, like on a temporary work visa - that is an expat. US/UK/Canada have a lot of treaty agreements with other countries, so a Canadian citizenship will essentially allow you into many countries more easily than those coming from a third world country. People from third world countries have to go through a more intensive visa process for temporary residence.

Another reason expat applies generally is because generally an expat from the US does not renounce their US citizenship despite the tax implications due to the need/desire to return home. The US is one of the few countries that will tax a US citizen anywhere in the world, which I think leads to the increased use of the word expat.

It got the ‘trendy buzzword treatment’. There was a time when people were using it pretty heavily to describe professionals with specific skillsets and expertise sent to foreign (usually emerging) markets where hiring locals might be spotty. There was a time when, if an expat asked a local where expats hung out, the locals would interpret it as them asking where the foreign professionals would hang out, and usually they’d all talk shop/share experiences, that kind of thing.

There are of course multiple definitions but the corporate world started flinging it around like such. If you were chosen to be an expat you were basically ‘A team’ material - smart, reliable, trusted with a generous amount of autonomy, that kind of thing.

But it conveyed some sort of prestige, like ‘entrepreneur’. Now lots of people use it loosely as a colloquialism to describe anyone from a dyed-in-the-wool immigrant to someone who took a 6 month sabbatical to have an extended vacation on a sunny beach

I hear the word expat all over the world, I don’t think it’s regional.

“immigrant” gives the impression that you are traveling to get to someplace, while expat implies that you are traveling to get away from someplace, as I’ve heard it used.

Colloquially, expat tends to imply self funded, or at least bringing wealth with them in some respect. That’s not what the word literally means but it’s how I see it used. This is consistent even with foreign professionals coming to work in, say, London. Few people refer to them as immigrants though that’s what they are technically. (I’ve seen people be called an “ex pat from their country” or an “international worker”, these both in the city of London referring to office based professionals) The word immigrant seems to be reserved (at least in Britain) as a pejorative because it implies low skill and by further implication, a net cost on public services.

Everybody is a foreigner in nearly every country on earth.

But, if you want to declare yourself as special, then you start to make up special terms.

Because its a better word