AGM battery or Absorbed Glass Mat technology , are engineered and designed similar to wet acid battery. however the technology made agm battery more useful in deep cycle application such as use in caravan and other Rv vehicles. agm battery is used in new cars with stop start function, or in demand of high computerised accessories fitted in cars.  because the fibreglass mat absorb the acid,
AGM battery is acid based but the fully absorbed glass make it spill free and more vibration resistant. the agm battery is more likely to have no leak and corrosion.