What's the difference between normal and Christmas beer? What's the difference between normal and Christmas beer? What makes them special?
A Christmas Ale seems to be another term for a "Winter Warmer" beer -- a dark, malty beer (raisins, dark fruit) meant to be enjoyed in colder months, with a warming effect, either from the actual alcohol, or spices it was brewed with (think nutmeg, clove, that sort of thing).  To my mind, its kindred to a barley wine, just spiced up.  This is not a warm summer day, sitting on the porch, type of beer, as you may have guessed.

So a Christmas Ale is a sub-classification of beers in general.