Why echo null==NULL; gives output as 1? Why it is not given output as word true? & also they are different cases.

Answer 1

because it is a logic statement like boolean and it is returning 1 because null is not case sensitive (nUll,Null,nuLl)they all mean null (0)

Answer 2

There it happens casting to integer 1 when you print it or use it in an expression.
If it false, nothing displays...

Edit:
This may help you..
Read from this, steve's explanation and next ones for more information...
https://www.php.net/manual/en/language.types.boolean.php