oh my gosh. what a question
i suggest that you get yoruself a copy of Jeff Imada's Advanced Balisong Manual. That rules and has a nice catalog at the back too.
oh yeah as for differences you can tell by the number:
40 series refers to 4 inch bladed productions
400 series are 4 inch blades with thicker custom like handles
30 eries are 3 inch blades with thin handles.
60 series are the pacific cutlry 3 inchers,
200 series have micarta
x39 & x59 series are the zamak handles skeletonized and plastic inserts respectively.. I think 600 series are 5 inchers, what else...you can predict a trend with the newer blades I think. the older versions have no real set pattern. IN general if it is a 3 digit number it is of thicker handles while 2 digits are of thinner handles.. 129 doesn't aopply it is a nice little intl series weehawk with die cast handles. I have to hold one of those before I die.
I am sure I missed a lot of stuff in there.
it's so fun thinking model numbers but I am a crazed fanatic.
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</A> If you play with love you will be heartbroken; if you play with knives you will [bleed]