[CentOS] is yum a complete substitute of rpm?

> Thank Robert and Ron, Could you list an example where I need to use
> rpm command alone? I used rpm to install stand alone package if that
> is the case.

This one illustrates the kind of information you rather get with the
rpm command (here the installed size):

# List RPMS ordered by size (biggest last)
rpm -q -a --qf '%10{SIZE}\t%{NAME}\n' | sort -k1,1n

Useful when you need to make room in an /usr partition for example