Concrete is to data as theory is to hypothesis. This is because data is concrete(or solid), and a hypothesis is a theory.
This is a type of comparison. Comparison is useful for distinguishing or likening entities.
Comparison can be employed in order to carry out many different functions, such as: distinguishing the focused entity from potential confusors; likening the focused entity to other similar entities; illustrating a particular property of the focused entity with the same property of another known (but not necessarily similar) entity.