Difference between <Doctype> and <!Doctype>

I recently gave an interview and was asked the question to tell the difference between
<Doctype>
<Doctype>
and
<!Doctype>
<!Doctype>
I searched on the net but there is no answer. Can someone help me with this?
2 Replies
Kevin Powell
Kevin Powell•5mo ago
afaik, <doctype> isn't valid, you need the ! in there
Killer🔪
Killer🔪•5mo ago
THE kevin replied himself.. Will remember this day forever and thanks a lot for the answer.