Amazon Echo Skill - Is It Needed?

I just migrated to Hubitat and added the Hubitat skill in Amazon Echo. But I notice that under Apps in the Hubitat portal, it allows me to install Amazon Echo App or Amazon Echo Skill. I think the former is only needed if I can't get the Hubitat skill for Alexa in my country, which is not applicable to me. Is that correct?

What is the point of Amazon Echo Skill in Hubitat? Is that another way of controlling how devices get added to Alexa?

You are correct. The Amazon Echo Skill in Hubitat is the mechanism by which your hub communicates and shares devices with Amazon. The Hubitat Skill in the Alexa app is basically just authorizing the communications between the two systems.

When you “enable” the Hubitat Skill in the Alexa App on your phone/tablet, you’re prompted to sign into the Hubitat Portal (and select your hub, if more than one). Doing so will, cause your Hubitat hub to automatically install the “Amazon Echo Skill” application on your hub. You can the use this app to determine which devices to expose to Amazon Alexa.

Note, thermostats are not yet supported. Switches, Dimmers, Fan Controllers (as dimmers), motion sensors, and contact sensors are all supported.