2 different recipes. Brands sell different pigment mixtures under this name, so they won't all look or mix alike. Compare the pigments below.
Who makes it
PV15 Ultramarine Violet1
- Holbein Artists' Oil Color No. H374
PB29 Ultramarine Blue + PV23 Dioxazine Violet1
- Daler-Rowney Georgian (student)Student No. D111014442
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.