They are related concepts.
The coarseness describes how summarized the data is.
 
Imagine three different sizes of rocks. The first, a huge mountain, the second, a (nice) boulder, and the third a pebble. The mountain contains a large amount of material. In our example, the data of an entire organization is summarized into a few key points that are used by the executives of the company to make decisions for the company.
 
The boulder is composed of a lot of material, but substantially less than the mountain. It is used by manager of teams who can make decisions for their teams to help them achieve smaller goals.
 
The pebble is composed of little material. It is usually generated by customers and people who work with customers. Every time a customer buys something in a store, they are adding one more pebble to that store’s material. This will be summarized into “a nice boulder” of data which will then be further summarized into a mountain.
 
The coarseness of the data is determined how the data is going to be used. The CEO doesn’t need to know that jane bought a pair of jeans from store clerk #0054359, but the CEO would need to know that sales are down 5% from last quarter. The manager of store clerk #0054359 would be interested in that because that manager can track the sales of that particular clerk and can help them improve.