"
succulent" is the general word for water storing plants. There are root
succulents (plants that store water in their roots like calibanus hookeri, fockea, kedrostis, and dioscorea), stem
succulents (like cacti, adenium, and pachypodium), and leaf
succulents (like sedum, sempervivum, aloe, and agave). Some plants are combinations like jades, which store water in stems and leaves. It's like squares and quadrilaterals; a square (sedum) is a quad (
succulent) but most quads aren't squares.