Below I have a picture of Classic C5, vs Bullet G5 vs Bullet B5 side by side.
For C5 in US, C stands for Classic and 5 for 500 cc. (In India it is called Classic 500).
Bullet has different frame from Classic.
Bullet designation is for B5 (in US), G5 (no longer made, but was sold in US), and Electra (UK designation of G5).
The battery cover or fuse box has designation printed on it - classic or bullet.