"Mold" vs. "Mould"
"mold" is the US spelling, "mould" is the British English spelling. No other difference.
Same applies for other meanings of mould/mold, i.e the fungus that grows on rotting substances, for example.
I'm from upstate New York and was schooled that 'mold' is the stuff that causes spoilage. 'Mould' is to form or shape. Moulding is the process of forming something or the formed piece itself, as in architectural moulding. A few years ago, our area finally got a Lowes store. I actually laughed out loud when I saw they had a sign claiming they had a 'molding' department! Yikes! Also a bit perplexed by all of the Spanish signage, especially since even our highway signs are written in English and French as we're only a few yards from Quebec.