As nouns the difference between unionist and loyalist
is that unionist is an advocate or supporter of unionism while loyalist is a person who is loyal to a cause, generally used as a political affiliation.
As an adjective unionist
is (sometimes|capitalised) of or pertaining to unionism.
unionist
English
Adjective
(
en adjective)
(sometimes, capitalised) Of or pertaining to unionism
Noun
(
en noun)
An advocate or supporter of unionism
A trade unionist
loyalist
English
Noun
(
en noun)
A person who is loyal to a cause, generally used as a political affiliation.