Is there a difference between saying that someone is "English" and that someone is "British"?
But then again I have heard it said that someone is "Spanish" which is not the same as saying someone is a Spaniard.
Of Course, you can say that someone is Chinese which may or may not mean s/he speaks Chinese but it means s/he is originally from China. .
Same with Japanese and Korean, You can say someone is Japanese and you can say someone speaks Japanese.
You can say someone is Italian but does it mean s/he speaks Italian?
Gaelic is spoken in Scotland. can you say that someone is Scottish and that someone is Gaelic interchangeably?
In Belgium people speak Flemish. To say that someone is Flemish does not seem to be the same thing as saying that someone speaks Flemish but it could mean that someone is from Belgium, a Belgian.