Basically they all mean the same thing, but there are shades of meaning between them. Example: 1. It was a sad affair between those two rivals. 2. It was a terrible criminal affair. 3. The company affair had been bad for business. But 4. It was a horrible business. 5. It was a shady business. 6. The Chicago business came to an end. 7.. I will have nothing to do with this matter. 8. The difference between himself and his wife had now become a matter of common knowledge 9. However he decided to deal with this matter or 10. The mechanism of a clock is a complicated affair. 11. They were flimsy affairs[ things], these cars.