When it comes to colored pencils, generally there are 2 main choices: wax based colored pencils or oil based colored pencils. I should note that the pencil lead will have additional components in it to give it it's special texture an color but generally speaking wax and oil are the 2 main bases.
Both wax colored pencils and oil colored pencils have their own unique attributes to them and often times people wonder which is best, wax or oil?
The answer of course is that neither one is better, they are just different and knowing the difference can help you decide when to use which one or maybe choose which one you personally prefer so let look at the attributes of each of them:
WAX BASED COLORED PENCIL LEAD:
This is the mostly widely spread, widely available type of colored pencils, most colored pencils you'll find are wax based. They are usually cheaper to buy and easier to find. They are also easier to erase if you made a mistake and similarly, they are also easier to shade or lighten when compared to oil colored pencils.
Because wax is a softer lead, these types of pencils lay down lighter on paper giving you the chance to draw using layers. However, when using wax based pencils, wax bloom can become a problem.
Wax bloom is an opaque white layer that builds over time on top of the colors you drew. Of course you can take measures to either avoid or fix wax bloom but that's for another article
OIL BASED COLORED PENCIL LEAD:
Oil based colored pencils are rarer and harder to find when compared to the ubiquitous wax based pencils. Oil based pencils are more expensive but they offer some good features: For example wax bloom won't be a problem, they are more durable because the pencil lead is harder and in turn that also makes these kinds of pencils easier to sharpen without fear of breakage. Because of the harder pencil lead, they also lay down a thicker coat of color which means you won't need to color using layers.
In conclusion, the differences between them aren't that big but they do exist. So now that you have an idea of what the differences are, go and try the two kinds and decide for yourself which one is right for you