What is the difference between these? Is the V18 the newer model or something? Are they both classified as Palominos? I can't see the V16 on their website anymore.

The Palomino series (V8/V16/V32) was discontinued. The Crate V series (V18 and whatever others) is its replacement.
Ibanez RGA121 | ESP LTD H-1000
Axe-FX Standard