Assuming that when you mean records, you have a single unique id value that is stored in the array, then you can do the usual trick of using a hash as a search mechanism:

my %temphash = map { $_ => 1 } @arrayA;
my @inBbutnotA = grep { !$temphash{ $_ } } @arrayB;
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If your record is more complicated, you have have to add another step to break out the unique id for either of these steps, but the idea is still the same.

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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain
"I can see my house from here!"
It's not what you know, but knowing how to find it if you don't know that's important