• Use the Organizer to copy styles from one document to another*
• Macro to copy styles from one template to another - Microsoft Community
• Working with Styles by Tony Jollans, MVP

* When you copy a style that uses Theme fonts / colors into a document, if the original document/template and the receiving document template are not using the same Word Theme, the styles may look different even though having the same style definition.

If a style is based on another style and copied, it will pick up the inherited characteristics from the style on which it is based in the receiving document. See first link about this.