Why is the deployment summary item count different from the selected item count?

As a new user of Gearset, we make come to expect the two counts to match. The two numbers are

However, this assumption is not true due to the way that the Salesforce metadata API counts items versus how Gearset is counting them.

Gearset decomposes the metadata into individually deployable parts. For example, one single profile in the metadata API can be decomposed into thousands of permissions that are individually changed.

Therefore, there is no guarantee that the numbers are identical as the reference different ways of counting metadata.