A common confusion is to equate "affections" with "emotions." But there are several differences, as summarized in this chart from McDermott (p. 40):
|Consistent with beliefs||Sometimes overpowering|
|Always result in action||Often fail to produce action|
|Involve mind, will, feelings||Feelings (often) disconnected from the mind and will|
He explains why affections are different than emotions:
Emotions (feelings) are often involved in affections, but the affections are not defined by emotional feeling. Some emotions are disconnected from our strongest inclinations.
For instance, a student who goes off to college for the first time may feel doubtful and fearful. She will probably miss her friends and family at home. A part of her may even try to convince her to go back home. But she will discount these fleeting emotions as simply that—feelings that are not produced by her basic conviction that now it is time to start a new chapter in life.
The affections are something like that girl's basic conviction that she should go to college, despite fleeting emotions that would keep her at home. They are strong inclination that may at times conflict with more fleeting and superficial emotions. (pp. 32-33)
Here is how Sam Storms explains the difference in Signs of the Spirit: An Interpretation of Jonathan Edwards' "Religious Affections:
Certainly there is what may rightly be called an emotional dimension to affections. Affections, after all, are sensible and intense longings or aversions of the will. Perhaps it would be best to say that whereas affections are not less than emotions, they are surely more.
Emotions can often be no more than physiologically heightened states of either euphoria or fear that are unrelated to what the mind perceives as true.
Affections, on the other hand, are always the fruit or effect of what the mind understands and knows. The will or inclination is moved either toward or away from something that is perceived by the mind.
An emotion or mere feeling, on the other hand, can rise or fall independently of and unrelated to anything in the mind.
One can experience an emotion or feeling without it properly being an affection, but one can rarely if ever experience an affection without it being emotional and involving intense feelings that awaken and move and stir the body. (p. 45)