Here are some old scans of slides I took some years ago. Not the best quality, but they do certainly depict typical Prosser beads. The right or lower card holds what are usually called "tile" beads.

Whereas a typical Prosser bead has the thick raised equatorial seam seen in the left card beads, tile beads have a seam that is placed at the thicker end of each bead—so the seam is that edge.

Slip-molded beads come out of two-part molds, and very likely had a reasonably obvious seam (that may be either longitudinal or equatorial)—but this is easy smoothed away before (or even after) the bead is fired. Usually a trace can be found. But slip-molded beads do not have the thick and obvious seams of Prosser beads (plus, they are ceramic!).

JDA.