Where "Paypal email address" is the one you use when you login to PayPal and "primary email address" is the one you use the most, day-to-day or would otherwise be checking frequently.
If the above definition doesn't make sense to you, try answering this question instead: If email is sent to the address you use to login to PayPal, will you see it promptly (within say, a few days at least if not earlier)?
Just trying to get some data for a project I'm working on. Any assistance much appreciated.
I keep it separate for security reasons.