What is the importance of documentation comment in java

Question

I don't understand what is the difference between the documentation comment and the multi line comment

Answer 1

They’re generally good for keeping track of a complex program.
I found this out the hard way: I wrote a multi-thousand line program with no documentation and came back to it a few months later, I had no idea what half of my code was responsible for. It took me hours to get the gist of it whereas a couple of single-line comments would have saved me all that time.

Answer 2

Also helps others understand your code.

Answer 3

I mean what is the difference between the documentation comment and the multi line comment