• Speed range — ORSHA410 runs 10–70 rpm, ORSHA510 runs 10–80 rpm — slow by design, because the point is gentle, complete coverage.
• Tilt angle — a shallow angle washes the whole membrane without letting the solution run off the platform.
• Platform and load — a non-slip mat holds staining trays, blotting boxes, Petri dishes and culture plates.
• Motion — see-saw rocking rather than orbital: the liquid sweeps back and forth across the surface.
• Continuous duty — rockers usually run for hours or overnight, so continuous rating matters more than top speed.

Use a rocker for anything flat that has to stay wet: blots, gels, staining trays, cell-culture plates. Use an orbital shaker when the sample is liquid in a flask or bottle and needs real mixing. Use a roller mixer when the sample is in closed tubes — blood, suspensions — and has to stay homogeneous without foaming.