Importance is the state of something being of significance whereas advantage means something is in a condition to be superior.
Explanation:
When we say "importance", we mean that that particular thing is of high significance. It is already valuable. But, when we say "advantage", then we meant to say that something is in a condition to be significant or superior.
Saying 'importance of something' is to imply that that thing is of great significance and it already is superior.
While saying 'advantage of something' means that thing is in a situation/ condition of being important/ valuable.
An advantage statement is one where the seller has assumed that the buyer has a need or requirement In other words, taking our previous example, if the customer had not specifically expressed a desire to use less disk space, then the previous statement is in fact an advantage and not a benefit. So the challenge for us as salespeople is to uncover what the customer actually needs, before we start talking about the "benefits" of our products. While I imagine there would be a number of sales people reading this and thinking "that's obvious - the rep didn't do his homework", I am constantly surprised at how often experienced sales people also fall into this trap.
In to kill a mockingbird scout says that Mr. Cunningham is a father like Atticus and caused the mob to quiet their anger and violent intentions. She kept asking innocent questions and she broke the murderous spirit the mob had. Scout made Mr. Cunningham stand in Atticus's shoes so he changed his mind.