What is the difference between сколько and как долго?

Do you know what is the difference between the question words сколько and как долго?

The first one literally means “how much” and can be used in context related to time or any other amount measured.

The second question is “for how long”, and it is used only when talking about time.

For example:

Сколько стоят эти джинсы? How much do these jeans cost?

Как долго ты здесь живёшь? For how long do you live here?