Discussion on the differences between Perl system (CMD) and ' cmd '

In Perl
There are two ways of system invocation, one is System (CMD) and the other is ' system '
Never noticed before, the difference between the two ways, and thought it was the same,
When I write a script today, I suddenly want to get the return value of the command, and then use the
My $result = System (' ls ');
found that the result of the command was not returned to $result,
It's straight, printed on the screen, so it's going to be a mess,
and change into
My $result = ' ls ';
The execution result of the command can be obtained.
So, if we are going to invoke the system command, and then we have to process the result of the command execution, we need to use
' cmd ', not system

Discussion on the differences between Perl system (CMD) and ' cmd '