St. John's is the
capital city of
Newfoundland.
St. John is the largest city (although not the capital; that disticntion belongs to
Fredericton) of
New Brunswick. The former is more well known, both in
Canada and internationally, and many inhabitants of the latter suffer from an
inferiority complex, often
exacerbated by the fact that St. John is larger than Fredericton, although not (nominally) as important.
The similarity between the two names does not help anything. If you want to make friends in St. John, you would do well to learn the difference between them.