Local - Pages and Page Templates
Your store's Pages are used for information that rarely changes but is used often for things such as an About page, Contact page and Shipping information. You can add as many pages as you like to your store admin under Pages.
There are also a few other pages like the Cart page that are generated automatically by Shopify, but have some customizable features. You can access these settings by navigating to the pages in the in the Theme Editor.
For more information on setting up pages in your store, see Shopify's guide on Pages
Page (default) - Maximum width of 600px
Page wide - Maximum width of 1000px
Page Service List - Use this template to add a Service List section to any page
Contact - This will append a contact form to the page content
Custom HTML - This doesn't include any formatting and allows you complete control of the spacing and layout. These pages require some basic html coding knowledge
For more information, see Shopify's guide on how to add HTML content with the rich text editor