Perl in a Nutshell, 2nd Edition

Equality operators

The equal and not-equal operators return 1 for true and “” for false (just as the relational operators do). The <=> and cmp operators return -1 if the left operand is less than the right operand, 0 if they are equal, and +1 if the left operand is greater than the right.

Numeric	String	Meaning
==	eq	Equal to
!=	ne	Not equal to
<=>	cmp	Comparison, with signed result