IMPORTANT NOTE
There is information on several pages on the internet about parallel and relative minor scales.
They say exactly the opposite about the names and characters of both scales.
In fact, the name is not that important, but to know how to find the right scale, that's what matters.
On this website we use the names exactly as we say it in Dutch:
RELATIVES as brother, sister and father are relatives with the same name, so also scales with the same name are relatives.
PARALLEL is what we call two roads in the same direction; "parallel lines never meet".
So,
RELATIVE SCALES:
C major - C minor
G major - G minor
D major - D minor
F major - F minor
PARALLEL SCALES:
C major - A minor
G major - E minor
D major - B minor
F major - D minor