@lxo @freetar @Suiseiseki @mjg59 honestly I don't see a hard and fast distinction. If I break the bottom bracket on my bike I could replace it with an identical component or I might put a better (lighter, stronger) one in. Especially for older items, the original part might no longer even be made and a different part would have to be substituted. If I take my holey jeans to the repair cafe maybe they put a patch over the hole - that's both a repair and a modification