Differences between creating a Site in SharePoint Dashboard vs. Admin Center

Question

I'm relatively new to SharePoint Online and I'm currently trying to understand site structures and best practices. I'm having difficult in understanding the site creation process within the Admin Console vs that of the SharePoint Online Dashboard.

From my understanding so far:

• Every site you create will always be a sub-site under a site collection root site unless you are creating a new site collection.
• You can create site collections depending on your needs within the Admin dashboard and then create sub-sites under the site collection root. The Admin Console gives a lot of options as to what sites should be created based on templates and URL.
• You can also create a new site under the Dashboard which seems to be a root/site-collection, but this approach is more simplistic and basic.
• Both features seem to instantiate root level sites with no sub-sites from what I can see as indicated by their URLs.
• Following the previous point, in checking the default site collection that was spawned on sign up, I'm not able to see any of the sites I created as sub-sites via the SharePoint Online dashboard.
• The sites created within the SharePoint Dashboard isn't showing up within the Admin Console for site collections however if they are actually root sites so I'm a bit confused about what's happening here.

Would there be any significance as to how the sites are created at all? Is there some sort of hidden site collection in which my sites are being instantiated under if I create sites via the SharePoint Dashboard?

Edit with Screenshots:

Creating site via SharePoint Dashboard:

New "Site Collection" with URL:

Not seen within Administration Dashboard:

Answer 1

Yes, what you have created is, what is nowadays called as Modern Sites, namely Modern Team Sites or Communication Sites.

These dont show up in the standard admin center.

But if you notice, there is Try the preview button just above.

Once you click on it, you will be redirected to what is now called as the new(or modern) Admin center.

On that page, you need to click on the Site Management link wherein you can see these Modern sites.

This is all fairly new and understandably confusing for users :)

Answer 2

You have one root site collection in the tenant which you can find by going to: https://[tenantname].sharepoint.com.

Any subsites under this site collection would be: https://[tenantname].sharepoint.com/[subsite] and those site can only be created from that site collection. Not from within SharePoint admin

By default in the modern SharePoint interface you almost always create a site collection. These url's look like: https://[tenantname].sharepoint.com/sites/[sitecollectionname] or (less used) https://[tenantname].sharepoint.com/teams/[sitecollectionname]

And of these sites are not subsites, but site collections. If you would create a subsite in one of these site collections the url would be: https://[tenantname].sharepoint.com/sites/[sitecollectionname]/[subsitename]

The current guidance is to not create subsites. Only create site collections and create a Hub sites to connect these together.