When you publish a page, it becomes visible to everyone who can view your site. If you don't publish a page, the only people who can see it are those who have edit permissions on your site.
After creating and editing a page, you can save it as draft, discard changes, or publish. Here's what happens:
Save as draft
When you save a page as a draft and don't publish it, any changes you've made during the current editing session are saved, and the page is checked in. The latest version of the page is in a draft state, and not visible to site users yet.
Discard changes
Any changes you've made during the current editing session are not saved, and the page is checked in. The latest version of the page is in a draft state, and not visible to site users yet.
Publish
Any changes you've made during the current editing session are saved, the page is checked in, and the page becomes visible to site users and available in search.