The divide between metric and imperial bikes is more than just different tool sets and measurement standards, as you're probably well aware. Still, this video from Paul Sr. and his crew at Orange County Choppers, as they get stuck into working on their build-off bike, makes the differences painfully clear.
If you haven't been keeping up, OCC is participating in a six-week bike build off with Bikes and Beards and the Bearded Mechanic, with all proceeds going to a charity they have yet to determine. It's also not clear if they're planning to auction the completed bikes off to obtain proceeds in the first place, or honestly what the entire plan is. Or maybe they've discussed it amongst themselves, but haven't yet made it public.
In any case, each builder in this challenge is dealing with a different handicap. OCC has been building custom bikes for a long time, but generally sticks to American iron for its creations. The Bearded Mechanic, meanwhile, primarily deals with vintage Japanese bikes, though sometimes he'll get an oddball European or other machine (think Pulse Autocycle) come through his garage.