User blog comment:Kirkburn/Technical Update: August 31, 2016/@comment-4568327-20160901140903/@comment-24473195-20160902125659

"Publish is better than Save Page. 'Save Page' on a wiki makes no sense: it's not like you are saving the page to come back to it at a later time before publishing."

Indeed, both legally, and in practice save is different from publish. In fact, the VisualEditor team seems to have plans to have a "save locally option" that will not publish the content to the web so that people can continue their work in the event of a power outage, accidental shutdown or network problems.

Possibly, in the future they could even allow someone to write the whole page "offline" and save it before eventually publishing it a few days later.