Each interval of any scale has a mode attached to it. For example, starting on the second degree of the A Minor scale, is the B Locrian scale.

Here is a list of the modes of the major and minor scales, notice how they're related:

In the key of C:


I - C - C Ionian (Major) Scale
ii - D - D Dorian Scale
iii- E - E Phrygian Scale
IV - F- F Lydian Scale
V - G - G Mixolydian Scale
vi - A - A Aeolian (Natural Minor) Scale
vii - B - B Locrian Scale


And in the key of Am:


i - A - A Aeolian (Natural Minor) Scale
ii - B - B Locrian Scale
bIII - C - C Ionian (Major) Scale
iv - D - D Dorian Scale
v - E - E Phrygian Scale
bVI - F - F Lydian Scale
bVII - G - G Mixolydian Scale


Hope that sort of explains things.

-Mike