Multi-Domain WordPress installation

Hi there,

I was reading now for some hours and found a lot of similar cases, but non that was fitting to my issue. I really hope you can point me to the right direction.
From what I understand so far, my problem is different from the multi-site feature of wordpress!?

I want to have a one wordpress installation that is able to serve two domains with a single backend login. Now comes the tricky part.
1) I want to decide in the backend (i.e. via checkbox, menü, or what ever) which pages are displayed in which domain. Some pages will be the same, some won’t.
The theme should be the same for both domains

Do you have any ideas how to achieve that?

Thank you very much for your help.