What is the difference between a page model and a section model

Both of these model typoes allow you to add drag + drop editing to areas of your site.

The only real difference between the two is any page model you create will require a unique URL to be provided. So these are best for the use case of integrating landing page building so content editors can create pages on new URLs.

Section models are identical, but do not require a unique URL each. You can still use URL targeting, but sections are not generating landing pages per say, but are more frequently integrated into existing pages or page types, to allow managing parts of the page visually.