I always see people who uses XMAS as a shortcut term and common abbreviation for Christmas. Okay, I've actually seen some here. Honestly, I've never used  the term Xmas  because I just don't feel like using it. I never want to omit Christ in Christmas although I am not very religious. But I love our Creator dearly. :)

Back to the topic, Christmas and Xmas are equivalent in every way, and yes except for their spelling and pronunciation maybe. The "X' symbolizes the Greek letter which is "Chi" which means Christ. So basically, it's still an acceptable term.

Merry Christmas everyone and may you have a fun-filled celebration! Spread love. Let's not forget that HE is the reason for the season! :)