Whats the difference between the first moderna shot and the second in efficacy? do both protect against hospitalization?

There is substantion protection starting 10-12 days after the first dose, with reduced frequency of infection, symptoms, severe symptoms, hospitalization, and death. However, you still need the second dose for maximum protection.

The first shot confers about 50% efficacy at 12-14 days, and after the second, efficacy climbs to 95%. So, the two together can make you almost "bullet-proof" (credit this to Johns Hopkins School of Medicine).