

No idea who came up with that last idea, I suspect that they work for Microsoft and were also responsible for the latest name change in the Office 365 SMB-tier product lineup. Home Assistant is a hypervisor with the capability to run Docker containers, and comes with the Home Assistant Core container pre-installed, which also acts as. What makes the whole thing even more confusing for beginners is a semi-recent name change from HassIO to Home Assistant, which also rebadged what was previously known as Home Assistant to Home Assistant Core. Home Assistant Core is what you have installed most likely, it's 'just' a management interface for your smart home, without the option to install Add-Ons that add more complex services. Those containers are what allows you to use the Add-Ons. Home Assistant is a hypervisor with the capability to run Docker containers, and comes with the Home Assistant Core container pre-installed, which also acts as the management interface. Home Assistant Core is what you have installed most likely, it's "just" a management interface for your smart home, without the option to install Add-Ons that add more complex services.

There are two different versions of Home Assistant: Home Assistant and Home Assistant Core.

I am afraid that you fell into a very common beginner's trap:
