A theme's fonts: one collection for headings and one for body text.
A collection is taken whole: one that is stated replaces the base theme's, script fonts included.
Optional
The heading fonts. Office calls these the Headings font.
The body fonts. Office calls these the Body font.
A theme's fonts: one collection for headings and one for body text.
Remarks
A collection is taken whole: one that is stated replaces the base theme's, script fonts included.