Real Grade kits are 1/144, the same size as HG, with far more detail and an inner frame. Bandai's Japanese grade page says RG pursues being genuine, with detailed part structure and surface texture (our translation).
For new builders
Bandai rates the RG RX-78-2 Ver.2.0 for ages 15 and over; most builders start with an HG.
The RG RX-78-2 Ver.2.0 of August 2024 is 3,500 yen before tax and rated for ages 15 and over.
Read Oct 14, 2026. The definition is ours; facts come from the pages above.