Here's a comparison for the different series from Bandai (read comment) : r/ Gunpla
CHOOSE YOUR GUNPLA : REAL GRADE (RG) VS HIGH GRADE (HG) — Steemit
Gunpla Grade and Scale 101 - Gunpla 101
Which Gunpla Grade is for you? Ultimate guide to Gunpla Grades!
Dances with Evas в Twitter: „Came to the conclusion today that I definitely prefer the Master Grade Tallgeese to the Real Grade. RG Gunpla is excellent, packing so much detail and articulation
NU Gundam Real Grade vs Master Grade : What's the differences? - YouTube
How to Choose the Right Gundam Model Kit – Gundam.my Blog