ΔE 16.6, loose: different enough that you should pick on purpose. Orchid Light is a little lighter, much more muted than Ultramarine Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Orchid Light is a little lighter, much more muted than Ultramarine Violet.
The same difference applies the other way round: Ultramarine Violet is a little darker, much more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Ultramarine Violet on the colour wheel See Orchid Light on the colour wheel
All matches: Ultramarine Violet equivalents · Orchid Light equivalents