Having looked quite thoroughly at both formats to write PIC2PIC (</cheap plug>) I'm in a position to offer an informed opinion here.
| AGI | SCI |
| Basic format | Vector | Vector |
| Virtual screens | 2 | 3 |
| Resolution | 320 x 190 | 640 x 400 |
| Colours | 16 | 256 (dithered) |
Mokalus of Borg
PS - They are pretty similar, overall.
PPS - One was based on the other, I assume.