You can use either in your Heading 1 style. I, again, recommend using the Theme +Heading font. Here are some Styles resources:

• Tips for Understanding Styles in Word by Shauna Kelly
• Why Use Word's Built-In Heading Styles? by Shauna Kelly
• Understanding Styles in Microsoft Word
• Managing Word Styles by Suzanne Barnhill, MVP
• [Quick] Style Sets and Word Themes in Microsoft Word