Quick and dirty, add all 6 bytes together into a word and compare that number to the 'new' number. If they're not equal, you know you've got a different button. If they're the same, you MIGHT NOT have the same button and have to do further comparisons.
Any way you go, you're going to have to do some comparisons somewhere...

A bit less quick and not so dirty, put those 6 bytes into 3 words and compare those 3 words the same way as above.

I don't know why you're against comparisons. PBP supports them just fine.