|Uhaul by Coulter|
Regarding both oils and acrylics, the degree of opacity or transparency may be very important to the effect you can create. For instance, most of the "new" synthetic colors, which can be identified by their unfamiliar names (such as quinacridone, napthol and hansa) are more or less transparent. They also tend to be quite a bit less expensive than the traditional organic colors, such as the cadmiums.
Not realizing this, for a number of years I bought the synthetics. They look as bright. But in the case of Red (for example) they don't cover as well as Cadmium and they interact with other colors differently when blending.
The jury is still out on this point. However, you (as artist) should be aware of the differences and perhaps allow yourself some of the more expensive colors (such as Cadmium Red Medium, Cadmium Yellow, Cobalt, etc.) for use when the brilliance of the color is important.
Some of the traditional colors, on the other hand, like Alizarin Crimson, were manufactured from plant dyes and are notoriously "fugitive" (they fade.) Alizarin Crimson has been replaced by Alizarin Crimson Permanent (which I don't find as delicious a color as the original). I buy instead, Quinacridone Rose, or Magenta.
I did not intend this to be a lengthy post, but I've been holding off for a long time, so you get an extensive regurgitation. There's a terrific book, if you like to read about this kind of thing, called Color: A Natural History of the Palette by Victoria Finlay. It's well written but is dense text. If you're more into experimenting then reading, I suggest you experiment with differences in Cadmium Red Medium and other warm reds in that band of the color wheel. Cheers.