What's the difference between HG, RG, MG, PG, and MGEX?

HG (High Grade) is 1/144 scale and beginner-friendly. RG (Real Grade) is also 1/144 but with an inner frame and MG-level detail packed in. MG (Master Grade) is 1/100 with a full inner frame and 200+ parts. PG (Perfect Grade) is 1/60, the largest and most detailed standard line. MGEX is a premium 1/100 tier with metallic finishes and extreme gimmicks, sitting above MG in price and complexity.