I just wanted to know about the advantages and disadvantages of "require" over "use" in Perl.

There are none, use use, use is require :)

I know that : list of things I kinda know

:D

is there any gain in terms of memory consumption when I use "require" or any other advantage ? Please let me know.

use is implemented using require ... they're one and the same

There are no gains in terms of anything ... its the same code

Difference between 'use' and 'require', Re^3: Moo error message not understood (begincheck.pl)