The Drupal 8 version of Omega contains an easy subtheme generator. Simply enable the Omega Core theme and visit the settings page for the theme. Then fill out the form:

Generator Options

The generator can be used to do two theme-building actions:

Clone

Creating a clone of a sub-theme will create a direct clone with minimal options for customization. The process will clone the entire directory, and search and replace machine names where appropriate to create a newly named theme identical in every way to the previous theme. This provides great potential for quick testing of a theme patch on your installation without risking any adverse effects on the primary theme.

There are also several checkbox options available for customizing your clone if you chose to go that route:

Enable SCSS Customizations

Subtheme

Creating a sub-theme will allow you to create a highly customized new theme based on another theme. The options available here will allow you to customize items like layout inheritance, template overrides, SCSS support and more. Each option includes a detailed description that should clarify exactly what will happen when selecting/deselecting an option.

There are also several checkbox options available for customizing your subtheme if you chose to go that route:

Inherit Layout from parent theme

Include templates from parent theme

Enable SCSS Customizations

Include customizable library with CSS/JS

Include samples in your .theme file

Include theme-settings.php