Purslane is Portulaca oleracea, there is only 1 kind. Other Portulacas have other common names, but any Portulaca is also likely to be called purslane or moss rose, the same way a lot of other Tradescantias besides T. zebrina get called wandering Jew.
Since there's so much confusion about which plant is purslane, (both by name and appearance,) and countless anecdotes of people eating the other Portulacas (because they think it is purslane,) I'm convinced they're all edible. Otherwise, there would be anecdotes of the repercussions of eating the other ones, and articles for foragers about telling them apart.
Over the years, in response to pics (so, not a problem with names,) many people have insisted they eat P. grandiflora, umbraticola, pilosa, and amilis. Just please make sure you never try to eat any Euphorbia (spurge) plants, some of which look very similar to various Portulacas. If you see white sap inside a plant, it is NOT edible, that's latex, and a definitive clue it's not any kind of Portulaca.
