CM server enable content editors to create and publish content to a web site.
CD server makes your web content available to your website visitors.
Database Access :-
Servers | core | master | web |
content management | ✔ | ✔ | ✔ |
content delivery | ✔ | X | ✔ |
The xDB ( MongoDB ) collects all online and offline customer interactions from all channel sources in a central database repository.