What is the difference between “-rw-rw-r– 1” and “-rw-rw—- 1” permission?

Consider the file detail:

-rw-rw-r-- 1 username username 3.2K Sep 2 10:12 header.png
-rw-rw---- 1 username username 22K Sep 2 11:32 footer.png

I got the output in the terminal using the ls -alhtr command.

The question is – which command will allow me to change the permission of the footer.png same as the header.png?