Greetings, Werner.

I can't imagine Knoppix as my #2 Linux.
It best meets my needs & lack of expertise.

I think your comment may be the best short answer
to the question of how Knoppix & Debian are different.

I can imagine more expert Linux users, certainly commercial
and professional users, may have other first choices.

Also, I count on you, KK and a few others on this
forum to keep me out of trouble.