Waxes are the most commonly known and its name is derived from the original Carnauba wax that really made it well known across the automotive industry. Waxes are typically fairly easy to apply (depending on how hard/dense) and provide excellent levels of gloss (that wet look). The one downside to waxes are their longevity. Most waxes last a handful of washes at the very most (particularly those with a higher content of Carnauba wax in them).
Coatings are a relatively new technology compared to waxes and sealants. They key chemical compound in it is silica dioxide (ceramic) and this provides a very strong bond between the coating and the paint surface. As a result it is a far more durable layer of protection. The downside with coatings are that they are fairly costly and can lack the level of gloss often seen in waxes and sealants. The main way this is overcome is through the application of multiple layers of the coating to build up that layer of depth. Another often quoted downside is the difficulty of application (which has now been largely overcome by products such as Nano Quartz that are made to be easily applied).
Sealants are somewhat in between the 2. Sealants are chemically synthesised and are very easy to apply with a greater level of gloss over single layer coatings but significantly more durable than waxes. Sealants also have the advantage of being more cost effective than coatings and are a great in between solution for customers who want a more durable product without having to jump straight to coatings.
In conclusion, each of these 3 classes of protectants have their own effectiveness and can will be able to provide varying degrees of protection to your paint. What you decide to go with will be determined by how important these factors are to you:
- Gloss factor
- Ease of application