Resins are liquids that can be converted into polymers (plastics) Sometimes this conversion happens naturally (Rosin Drying out) and sometimes it is catalyzed by a chemical interaction.
They can be grouped by various properties but for our purposes we're focused on their heat resistance. Which we split into two categories.
Plastics that deform when heat is applied, used in Vacuum forming, Injection molding, 3D printing. These plastics are widely used in industry due how easy they are to form in production.
Plastics that chemically polymerize and are set in their shape during that process. Adding heat can sometimes soften them a little but, but the polymer chains remain until they are broken down by catching on fire or denaturing. These plastics are cast into their final form and resist heat well.
