From a dictionary definition viewpoint, which really is far from a satisfactory answer as there are deeper explanations for both…but just to give you an idea:
Love
-a profoundly tender, passionate affection for another person.
-a feeling of warm personal attachment or deep affection, as for a parent, child, or friend.
-a person toward whom love is felt; beloved person; sweetheart.
Compassion
-a feeling of distress and pity for the suffering or misfortune of another, often including the desire to alleviate it
-mercy