>>6784194You can see the difference between cacti and succulents pretty easily. This Stetsonia has clearly defined ridges with equidistant points ascending up a column, with each point growing spines in particular directions. All of those things are basic characteristic of cacti. There are some exceptions though, like Echinopsis Scopulicola, which looks similar to the common San Pedro cactus, except as it grows, it's spines become shorter until they disappear at around 1 foot tall, then they spend the rest of their lives having no spines.
tl;dr all plants are pretty different from one another, but there are a lot that superficially look very similar to other species of plants
