While the books and the TV show share many of the same characters and general story lines, there is enough of a divergence in both to deem them alternate realities. There appears to be many more fans of the TV show who have never read the books (and hence don't know what all the fuss over characters and plot is about). I'm sure it is possible to be a fan of both realities, but any attempt to reconcile the two will ultimately prove to be frustrating and futile.