Publishing
How publishing freezes a snapshot, and why your edits never disturb a live form.
Publishing takes your draft and freezes a snapshot. The public form always renders that snapshot, and every submission is validated against it on the server.
Editing after publish
Keep editing freely after you publish: your changes stay in the draft and do not touch the live form until you publish again. So someone answering your form mid-way is never disrupted by an edit.