Yes, you have to install the module "Odoo Multi Website" (https://store.webkul.com/Odoo-Multi-Website.html)

and configure your Nginx Server with the correct domains.

It's a matter of "alias".

So, in this configuration you will have only one database, but different domains --> different websites that are indipendently:

- they can have different Theme Template

- they can share the views or not (there will be a filter name "Website" to specify in which website this view will be for.

The users can do login in both.

So you will have something like 

- subdomain1.DOMAIN.com 

- subdomain2.DOMAIN.com

I hope this helps some users.

As Odoo has the frontend (website and e-commerce) and the backend integrated by default, there is no separate domain for the backend and the frontend by default. The default URL for the backend is yourdomain.tld/web.