a subset of affect.
a microbe for instance can be affected towards food by simply reacting chemomechanically to gradients in its environment.
when the struggle for life takes bigger forms affection becomes more sophisticated.
and we categorise it according to the timeframes in which it plays its role.
emotion happens on a rather short timeframe
moods can take much longer
fortunately we are blessed with love, which can rage passionately in a matter of minutes or even seconds, and which can last a lifetime, leaving us without words to describe our loss and therewith defying this silly need to categorise things that do not need categorisation. just stick to the truth, and you'll be just fine. Be brave!