When it comes to understanding your vehicles paint, there are two types in general. Single stage and base clear or also known as urethane paint. Most cars today are painted base clear which is as simple as it sounds. The first coat is the color/colour of your car then roughly after 10 mins it is sprayed with again with paint that is clear. This system has replaced single stage paint as it is more chip resistant and more durable than single stage paint. Urethane also has a nicer finish to the eye for most people. This type of paint system you will find on most of your cars from the last 20 years or so.
Single stage paint however, comes in acrylic lacquer and acrylic enamel. Acrylic lacquer was used from the 20's to the 60's and was considered soft because when the paint was expose to UV and chemicals durability seemed to be a issue. This was due to the system not having really any chemicals in the paint to harden it. During that same time period Acrylic enamels were use even more so, this was the most common of the two as enamels were oil based and the chemicals in it made it more durable than lacquer.
Both Single Stage and Urethane paints have pros and cons to them. Now take into consideration these vehicles come painted from a manufacture and not a custom paint shop the below applies.
URETHANE PAINT- Cars painted today
PROS: comes in great colours, very durable, UV resistance is mixed into the clear coat giving max resistance at the surface (* Until that clear coat is gone)
Cons: Can only be polished less then half as much of the life of the paint as Single stage due to the clear being sprayed up top. Lose %50 of UV clear coat resistance roughtly every 5 years ( a bit more in Australia due to higher UV index on average then most of the world)
SINGLE STAGE PAINT- Cars painted from roughly the 80's and back
PROS: Generally last longer then Urethane due to the UV resistance in the formula is mixed through out the paint rather then just the top layer. Can be polished more then Urethane and cheaper to repaint the vehicle on average.
CONS: Not as hard wearing prone to stone chips easier and scratching. Oxidation occurs rapidly as it has less UV inhibitors as a whole.