Ex-pat: someone who organises their move to another country, with finances and a job in place (unless retirees relying on savings) and having taken steps in advance to rent / purchase a home;
Migrant: typically not an organised relocation as described above. No pre-existing plan for housing or work, very limited existing finances (if any). By default, a far larger proportion of people fleeing persecution or war will do so in such a hurried fashion that they cannot take the steps that would facilitate an orderly move to another country.
It is vitally important to accept that there are a VAST range of factors that will contribute towards someone finding themselves in the position of being a migrant, and that some people are more likely than others, by merit of their birthplace and upbringing, to have the luxury of being ABLE to organise their affairs to the degree necessary to take the approach that I've described as an ex-pat.
It's not fair, and far more should be done to improve life for those in desperate need. But the terms "ex-pat" and "migrant" are not interchangeable, nor are they differentiated solely on skin colour. That's a simplistic view which does nothing to solve the issues and serves only to fuel the divisive narratives that various governments and opposition parties thrive on to drum up support.
The people massing on the Belarussian / Polish border are not ex-pats, they are migrants. But this is not because of their racial, religious or cultural heritage, it's because of the circumstances that forced the hurried departure from their previous homes.
IMHO.
