A difference is if one eats an apple or banana, one gets some fiber and substance to food that probably satiates appetite more than straight sugar does. Most of the calories in peanut butter come from fat - this probably satiates hunger more than eating the equivalent amount of sugar as well.

But there are as much fiber in potatoes as in bananas. Both foods are similar. So excluding potatoes (as in example above) makes no sense to me...

How do their micronutrient profiles compare?

Sorry, I was only responding to the immediate comment about apples and bananas.

A banana has 30g carbs (15g sugars), while the Trader Joe's peanut butter I am looking at has 7g carbs (2g sugars) in a 32g serving.