A way to distinguish these is there will be a estimate on the tube. The more high-priced paints are considered "Artist" quality and the colors can be very rich and the paint works and turns out much better. The quality of the pigments are lower and the paint is regularly loaded up with more "filler" and medium than actual quality pigment. The economy paints are considered "Student" quality paints and are decent to use when experimenting. The paint available to you ranges from the very cheap to the very expensive. If you're just starting out you can get away with using a smaller size tube such as 8 or 12 ml, but you'll find the suitable size is 37 ml. Most of my paints are from Winton, and a few from Grumbacher (a microscopic more expensive). This is a versatile and good looking earth color which can be added to a estimate of colors to darken them (never add black to darken a color, this will ruin the color- more on that later). Adding a microscopic white to these transparent colors instantly makes them opaque.) I also keep a 200 ml tube of burnt umber around. It is the base of every light color mixture, lightens everything, and helps turn sure pigments opaque (Some pigments like burnt sienna and Alizarin crimson have a very high transparency, that is they are roughly see-through unless applied in very thick layers. White is the estimate one color you will use.
I use 37 ml oil paint for most of the colors but I all the time have 200 ml for white and burnt umber. That way you regularly can't go wrong with the color selection. As I mentioned before a good bet is to get one of those starter kits that range in sizes and price. One material I think we can all agree you can't do without is the paint.