Hello,
ACCENT BUTTONS. Buttons that are directly related to the WooCommerce purchase functionality.
DEFAULT BUTTONS. All others, such as WooCommerce, supported plugins, and theme options buttons that are not included in the above category, and those buttons that do not have their own button settings.
For the advanced button styles, please follow this guide: https://xtemos.com/docs-topic/advanced-button-styles/
To change the button color, If you choose Predefined color > Primary in the Button widget, it will automatically use the Primary Color that you set in Theme Settings > Styles and Colors > Colors > Primary Color.
This is how WoodMart links the button color to the theme settings, so any new button using the Primary color will match your theme without needing to customize it manually.
Best Regards,