Products can be differentiated by physical features, location, intangible qualities and:

1. Differentiation need not be a difference a laboratory could measure. 2. Products are distinguished in several ways before being called differentiated. 3. Perception is one of those ways, alongside physical features, location and intangible qualities. 4. We call products that are distinctive in one of these ways differentiated products. _Source: OpenStax Principles of Microeconomics for AP(R) Courses 2e (CC BY 4.0), Ch 10 'Monopolistic Competition and Oligopoly', sections 10.1-10.2_