Typeface
A family of letters drawn to one design, such as Georgia or JetBrains Mono.
See it in Text flow. Switch Font between System sans, Serif (Georgia) and JetBrains Mono.
In plain words
A typeface is one design for a whole alphabet, with numbers and marks. Georgia and JetBrains Mono are typefaces. A font is one file of that design, often at one weight, such as Georgia Bold. Typefaces give text a voice: some feel formal, some friendly, some technical. Picking one for headings and one for reading is a big part of design.