That seems accurate to me. There is also another class of postponement you can apply for if you don't get a deferment, which is called a forbearance. Generally it involves calling the loan servicer and asking nicely. The main difference is that interest will still accrue with a forbearance.

Here's an example: https://www.acs-education.com/CS/Jsp/loanoptions/ffelForbear...

That one even has an online application form for the "Financial hardship" forbearance which is basically the "I just don't feel like paying my loan right now" option.