The core distinction feels rooted in source of power and narrative function. Traditional vampires are usually tied to a curse, a biological infection, or some Gothic 'rules' of the undead—their struggles are often about hunger, morality, and surviving in the shadows of a human world. Vampire gods, especially in recent paranormal romance or dark fantasy, ascend beyond that. They're less creatures constrained by a condition and more like deities who happen to consume blood. Their power isn't a side effect of being a vampire; vampirism is often a facet of their divine nature. Think of them as moving from being apex predators to becoming forces of a pantheon. They might create other vampires not just by biting, but through will or ritual, and their conflicts are cosmic: rival gods, shaping realities, or enforcing divine laws over entire supernatural civilizations.
Take a series like the 'Fever' universe—while not strictly vampires, the tone shifts when you get beings like the Unseelie Kings who feed on life essence. They're less 'vampire' in the Anne Rice sense and more primordial forces. A vampire god in that mold wouldn't hide from the sun; the sun might obey them. Their narrative role shifts from the monster we fear or sympathize with to the ancient, inscrutable power we might worship or seek to overthrow. That changes the whole dynamic with human or mortal characters; it's not a forbidden romance with a troubled soul, but potentially a devotional or apocalyptic relationship.
I find the trend fascinating because it blends two very potent mythological veins. It sometimes risks losing the visceral, personal horror of traditional vampirism, but replaces it with a different kind of awe.