What's the difference between kill and killall

The difference between kill and killall

I tried kill command as

$ kill "PDF Expert"
-bash: kill: PDF Expert: arguments must be process or job IDs

It report error,
However, when test with

$ killall "PDF Expert"

The application "PDF Expert" was closed.

What's the difference between them?

1 Answer

Kill works by process ID but, Killall can determine process by process ID it means if you give process name instead of process id you killall might find the process id and kill it.