What does magnetic field difference mean?

Magnetic field difference refers to the place where the magnetic field strength is not enough. Magnetic field difference means that the magnetic field strength is less than zero magnetic force unit n/a bar m. In a very weak magnetic field, the magnetism of molecules will affect physical properties. Magnetic field is a kind of invisible, intangible and objective special substance, which can produce magnetic force to the small magnetic needle placed in it. There is a magnetic field around the magnets, and the interaction between the magnets is mediated by the magnetic field, so the magnets can function without physical contact.