When programming in a strongly-typed language, you get it drummed in at an early age that you never, never compare floating point values for equality. So C coders might invent some way of representing how close they expect the values to be to be as good as the same, for example you might say that 0.1% difference is not worth worrying about: (pseudocode)

if ( (( x - y ) / x ) * (( x - y ) / x ) > 0.001 * 0.001 ){
  ## they are different
}
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Now Perl with its weak typing lulls us into a sense of security, especially with behind the scenes extras like only converting the sensible part of a floating point number into a string. So instead of the shenanigans of the strongly typed language, use Perl's behind the scenes extras by comparing the strings:

print "$x and $y are different\n" if ( $x ne $y );
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You will see you don't even need to coerce the values to strings, let alone printf format them, just use eq and ne directly!
iakobski