ΔE 8.0, close: similar, with a visible difference side by side. Ultramarine Blue is a little lighter, cooler than Dream On.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Ultramarine Blue is a little lighter, cooler than Dream On.
The same difference applies the other way round: Dream On is a little darker, warmer.
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 Dream On on the colour wheel See Ultramarine Blue on the colour wheel
All matches: Dream On equivalents · Ultramarine Blue equivalents