Gallery VS Portfolio

  • Gallery Gallery feature is for showing groups of pictures on your website. Therefore, this feature supports only image contents and also you can easily upload multiple images into gallery.
  • Portfolio Portfolio feature is for displaying your works on your website. Therefore, this feature support various types of content including text, image and video (Youtube, Vimeo, Self-Hosted Video and Custom link)

Page Template VS Content Builder

In order to create a page on your website. There are two ways to generate this page including Page Template and Content Builder.

  • Page Template 
    • Theme provided page templates which are designed all contents of a single page. If your requirements are matched the predefined page template that theme provided. You just select that predefined page templates after creating a page on your website.
    • In some page templates such as blog, gallery, portfolio, testimonial, team member and pricing, you should to prepare the contents before you select page template in order to display these contents.
    • You cannot change any layouts of this page template.
  • Content Builder 
    • Theme provided the content builder for generating the complex layouts and various type of contents in a single page. The contents can be text, images, gallery, portfolio or/and blog that are mixed together in one page.
    • However, predefined template will be also provided in this content builder in case your requirements are match this predefined template.
    • Moreover, content builder has two modes to develop including classic editor mode or live preview mode.
      • For classic editor mode, you will develop the content faster than live preview mode if you familiar with our builder. This is because you are not necessary to wait for loading preview page.
      • On the other hand, the live preview mode allows you to see the result instantly after you select predefined template or build contents of your own in this content builder.
    • In some types of content such as blog, gallery, portfolio, testimonial, team member and pricing, you should to prepare the contents before you select that contents in order to display the result in live preview.
    • You can change any section of this predefined template by using content builder.

Post VS Page

https://en.support.wordpress.com/post-vs-page/

Child Theme

https://codex.wordpress.org/Child_Themes