But... It's possible to informally celebrate both, as I plan on doing, Ruro! Eat candy from strangers and, two days later, the pancreas-killing skull! It truly is the life everyone should strive for.
Of course, being nowhere near Mexico or my relatives, I'll likely have a 2nd-rate candy skull. I was only in Mexico for the actual holiday when I was 5, but I still remember what the real candy skulls were like... Oh, and I remember trick-or-treating then too. I was a skeleton~