The biggest difference is the drum size. H-Wash 300 models range from 7-10kg – enough space for around 3 or 4 people’s clothes – while H-Wash 500 models have drum sizes up to 14kg. This’ll give you enough space to wash up to 6 people’s clothes at once, so if you’re in a large or busy household, the H-Wash 500 is for you.