How is this different from a regular Communication site?
Is it just that these three specific functionalities will be enabled when you set a site as a Home site?
It's easily accessible from the SharePoint mobile app for Android and iOS. All users that have access to the home site will see a home button on the Find tab of the mobile app. Being communication sites, home sites are designed to be mobile friendly from the start.
Search for the site is scoped to all sites within the organization. Having a great search experience is critical for the success of the home site.
The site is automatically set up as an organization news site. (Although you can have only one home site, you can have multiple organization news sites.)
Are there plans for additional features or functionality that will further distinguish a Home site from a regular Communication site?