What is the difference between lipstick and lip rouge? And are they used for different purposes?

Historically, rouge was used as early as in ancient Egypt. It was also applied on the lips, the way lipstick would be used today. In some times and places, both men and women wore rouge, such as during the Regency period in England.

https://en.wikipedia.org/wiki/Rouge_(cosmetics)

It should probably be noted that lip rouge can also be purchased in the form of lipstick and in pen form.