What is difference between PVC , ABS , VINYL and RESIN ?

Polyvinyl Chloride (PVC)
 - Low cost  
PVC is the one we are most familiar with and the most widely used: it is cheap, easy to use and easy to paint. If your figure model needs mass production, then PVC is the best choice in terms of the manufacturing cost. The PVC molds are also easy to reuse. 

- Temperature and Pressure Resistance  
PVC figure models have low resistance to high temperature and high pressure.
It means that they may have problems in a heated environment.When pressure is applied, PVC is more likely to bend and deform than to break. As time goes by, 
figure models made of pure PVC tend to have tilt problems (especially bigger appearance). 

- Safety 
Keep small PVC models away from children! PVC contains harmful additives,
which may be dangerous if ingested. Of course, our beloved PVC figures are not toys, and like any complex model, don't mess around. 

- Plasticity 
High-quality PVC material can overcome the tilt problem by condensing and increasing density. But due to its low heat and pressure resistance, PVC has considerable ductility. If the PVC model will encounter any structural problems (tilting or bending) in the future, it can be carefully corrected by heating and shaping. If you need to apply color to your PVC figure model,then basic acrylic paint can stick to it perfectly. Because PVC has strong and malleable plasticity, 
there is no wonder why it is so widely used.

Acrylonitrile Butadiene Styrene (ABS)
ABS is very different from PVC. One of the biggest differences from PVC is that ABS is very tough. If you have ever stepped on Lego bricks barefoot, then you will know how tough ABS is.Therefore, LEGO has even created its own slippers also specially produced exclusive slippers to less hurt when accidentally step on.  
Then again, there aren't many action figures made of ABS alone. 
ABS is tough, but it has its drawbacks. ABS models are NOT suitable for painting directly, and primers are usually applied in advance. ABS is also very smooth, which is not ideal for complex fine details. Although ABS has a certain degree of flexibility, if enough pressure is applied (rather than bending), it may break. Leaving the ABS figure model in direct sunlight for a long time, this will cause the ABS to fade and become brittle over time. Even though ABS is known for its toughness, always consider the environment to be used. ABS is usually used for the load-bearing part of the figure model, such as the legs or base (such as the ABS base of Dr. 
Akagi above). When combined with PVC, ABS can be used for the basic structure of the statue, while PVC can handle more complex details or shapes. To ensure that there is no tilt or deformation, most of the figure models are made of ABS and PVC.

Resin MOLLY sample, POPMART Resin / Polystone / Coldcast
These three materials have many similarities, but they also have different individual properties. They are structurally strong; however, they are generally brittle and prone to breakage if broken by mistake. All three are also more resistant to temperature and humidity. 

[Resin]
Resin has the smoothness of PVC, but it cannot be painted easily. Therefore, like ABS, the resin must be primed before coloring. The resin is easy to sand and cut, and can accommodate details as well as PVC. In fact, due to these characteristics, 
many GK model kits are made of resin. Since they are cast from flexible molds, 
resin statues do not need as many slices as PVC statues. Resin is also heavier than PVC and has a stronger feel to the material. However, the packaging of the resin model must be sufficiently shockproof, otherwise the resin is likely to crack or break. 
[Polystone] (a.k.a. artificial stone) and [cold casting] look similar to porcelain. 
Polystone is a compound of resin and tends to be more brittle, but at the same time, a lot of small details can also be expressed with Polystone. The texture and weight of Polystone are comparable to real stones. This impressive texture and ability to display details is generally the first choice for collectors, 
which is why Polystone is one of the most popular mass-produced resins. 

[Coldcast]
Coldcast is a resin mixed with metal powder. The finished product performs very well, leaving a deep impression on people. The mixture hardens for a long time, hence the name. Although these materials are not as popular as PVC or ABS, they have their own unique qualities and should be considered. Although they are more expensive, compared with other plastics, these three materials can provide an amazing visual difference 
for the model.