In the season 2 episode "What's my line (pt 2)" Spike says that they need the full moon for the ritual to restore Drusilla's health, however Giles says that they need the new moon, Spike later says this also, so which is it?
I'm not sure, but isn't a full moon also a new moon? Unless you're taking the full moon as the end of the phase and thus the new moon will be no moon (???) Now I'm so sure...
Full Moon refers to when the Moon's completely lit up by sunshine, so we see the full thing. At New Moon, it's just starting the cycle, which lasts 29 and a half days. It's hidden in the Sun's glare, so it looks like there isn't a Moon at all. See? Difference. Maybe when Spike first said Full Moon, he merely got it wrong...not as a script error (though it easily could be), but as the character's error, and he realized later that it was in fact New Moon. Why deny Spike the right to make mistakes?