What is the difference between KEYWORDS and RESERVED WORDS?

Screen Link: https://app.dataquest.io/m/577/coding-with-style/4/reserved-words

The above screen considers SELECT to be a reserved word. But I thought they are called keywords. Are they both the same? Or is there any difference?

In practice, they are both the same thing, but from a definition standpoint they are different. This stackoverflow post explains it very well: