The following are grades used to categorize Bandai’s Gundam plastic model kits (Gunpla) and some other Bandai model kits;
High Grade (HG)
Bandai’s most common type of kit. Typically in 1/144 scale (Usually around 13 cm tall). Rarely feature inner frames and potential for panel lining is there but limited. Most of these have polycaps (soft plastic) for joints so articulation is decent but due the smaller size and fewer parts, is limited. HG kits are separated out into different lines by their respective series. Cheap and easy to build, HG kits are great kits for beginners.
Real Grade (RG)
A newer line created by Bandai which features 1/144 scale kits the same as HG but in much higher detail. These kits are usually around twice the price but this is reflected by the quality. They have detail comparable to MG kits and have inner frames. New printing technology is used throughout these kits allowing parts to be molded in more than one color.
No Grade (NG)
Manufactured by Bandai. NG kits come in many different scales and range from very low articulation/detail to moderate. Some require glue and paint but others are snap fit and molded in color. This grade is essentially for anything that doesn’t fit into an existing grade. Recent NG kits are often on par or better than HG kits.
Full Mechanics (FM)
A sub category of NGs, currently only consists of suits from Mobile Suit Gundam: Iron-Blooded Orphans 2. These kits are 1/100 scale and feature an inner frame. The inner frame has more articulation that HG kits but is lacking in comparison to MGs. The inner frame is very similar between all FM kits.
Master Grade (MG)
Typically in 1/100 scale (Usually around 18 cm tall). Often features an inner frame and has many points of articulation. Many master grades also include a cockpit with a hatch that opens and unpainted figures of the pilot/s (1 seated, 1 standing). These kits are molded in many different colors and look excellent even without paint. MGs often have many fiddly parts and can take a long time to build. Having some experience is recommended before building an MG kit. MGs are generally more than twice the price of HG kits as many more gimmicks are included as well as been much bigger.
Perfect Grade (PG)
Bandai’s flagship kits. Usually standing close to twice the height of an MG in 1/60 scale, these kits are the pinnacle of articulation and detail. They are often 2-3 times the price of a decent MG and are molded in many different colors. There are many expansion sets you can get for these kits such as an LED kit. These kits take a very long time to make and are not recommended for beginners.
Super Deformed (SD)
No scale model kits that have disproportionate features such as a big head and small arms and legs. Are usually very easy to assemble. Some parts can be used on 1/144 HG kits.
High End Master Model (HMM)
Made by Kotobukiya for the most detailed Zoid model kit range. High detail, high articulation, usually in 1/72 scale. These kits do not come cheap and are often hard to come by.