Salesforce has so much terminology it can be a bit overwhelming in the beginning. I am starting a series of short posts to help me learn the definitions.
Salesforce has archived the Aura open-source UI framework
They were replaced with Lightning Web Components around February 2019. Aura components and LWC can coexist and interoperate on the same page.
Aura components
are the self-contained and reusable units of an app. They represent a reusable section of the UI, and can range in granularity from a single line of text to an entire app.