Web site with admin panel

I want to build web app (Angular + NodeJS) with some admin panel. I'm thinking how should this architecture look like:

• two web apps both with its own backend connected to the same database
• one backend with two Angular apps
• one backend with one Angular app and seperated modules for site and admin panel
• something else?

Does the admin panel should have different domain or subdomain? If yes, then the answer should be two backends. I will be grateful for advice and maybe some examples.