I got a new bottom bracket for my Brompton to replace the one I've been using for some years now and was making creaking noises on one side — trying another crank + pedal didn't solve the problem, so it looks like it's the BB.

The local Brompton store was out of Thun BBs, so I got a cheap, no name BB that was available in another store.

Unfortunately, it doesn't say if it's ISO or JIS, while the crank expects JIS.

Confusingly, some sites say it's important to match crank and BB, while others say cranks can take both these days.

Both shapes look very similar: Is there a sure-fire way to tell if a BB is ISO or JIS?

Thank you.