Help needed with identification.

I'm installing a safety hand rail in a shower. It's an older home and I'm cautious about drilling into the tiles as they may not be replaceable. A quick look at a tutorial on line, suggested I would need a different drill type if drilling into porcelain tiles as against ceramic, suggesting a diamond-tipped bit. (is this true?)
I perused the shelves at the green shed and found a suitable diamond tipped bit, I thought, but it stated on the label, "Ceramic".
How do I tell if my tiles are Porcelain or Ceramic?
And if they really are porcelain, what kind of bit will do the job?
I don't get a second chance at this..