The screenshot below shows a comparison of the \es-base-code\main\default\ source code structures for the Salesforce sample application Easy Spaces - Lightning version v. Lightning Web Components version. I need to do more digging into the source code, but is it accurate to say that the LWC version has added 1 new Lightning component (using LWC - named InlineMessage) to the \es-base-code\main\default source code found in the Lightning version?
export default class InlineMessage extends LightningElement ...
The second item under default\lwc, '\pubsub\pubsub.js' does not contain an export of a class which extends LightningElement.
The reason I'm asking this question is that it doesn't seem that the LWC version of the sample application has converted much of the regular Lightning - Aura version to LWC. It would be nice to have 'Aura' framework component code to compare side by side with the LWC versions of similar functionality.
In reference to @sfdcfox 's answer re pubsub and events, I did notice the following comment at the top of file
pubsub.js : /** * Component for basic, pub-sub sibling component communication. * This component is a stop-gap until a standardized system for * flexipage-based sibling component communication is available. */