Okay, let's think about this because my shelves are weirdly split between like, super dark urban fantasy series and a whole separate Kindle library for... other stuff. In UF, the alpha is usually a political title or a biological imperative. Think 'The Dresden Files' or Patricia Briggs' werewolf packs—the Alpha is the leader responsible for territory, law, and protecting the pack. Their dominance is a burden, a duty. The tension comes from balancing that brutal responsibility with staying morally grounded.
In erotica, the alpha label is shorthand for a personality archetype. It's less about leading a community and more about an unapologetically dominant, possessive, and hyper-competent love interest. The focus is on the dynamic between him and the protagonist, and the power exchange is the core fantasy, not a side effect of world-building. It's a vibe, not a job description. Honestly, the overlap can be awkward when a book tries to do both and the alpha just comes off as a controlling jerk instead of a nuanced leader.