Yes there is a difference but not so much in the meaning but in the spelling.
Mold is the American spelling for all senses of the word meaning, among other things, (1) a frame for shaping something, (2) to shape in a mold, and (3) any of various fungi that commonly grow on organic matter and are often associated with decay. Mould is the British spelling. American English has no mould, and British English has no mold.
Australian and Canadian English favor the British spelling, though mold is fairly common in Canadian publications.
Dictionary:
mould UK (US mold)
noun
- a growth of minute fungi forming on vegetable or animal matter, commonly as a downy or furry coating, and associated with decay or dampness.
- any of the fungi that produce such a growth.
verb (used with or without object)
- to become or cause to become overgrown or covered with mould.
Origin of mold
1150–1200; late Middle English mowlde, apparently noun use of variant of earlier mowled, past participle of moulen, mawlen to grow moldy, cognate with dialectal Danish ‘mugle’ (pre Harry Potter I presume?)
Thesaurus: synonyms and related words:
- Bacteria
- moulds
- germs
- viruses
- adenovirus aerobe
- amoebic
- antimicrobial
- bacteriological
- bird flu
- botulism
- germ
- lichen
- mycologist
- mycology
- nitrifying bacteria
- nitrogen-fixing bacteria
- norovirus
- nosemosis
- puffball
- salmonella
- superbug
- toadstool
- toxin