But the actual buildings of churches and mosques are quite different. The only ones that are similar tend to be newer constructions or were previously the other thing; e.g. the Hagia Sophia.
I think ultimately it just matters your comparison tolerance levels. You could just as easily make the argument that most churches are different from each other as well.
In my opinion, churches/mosque/temples are very similar because I live in a younger part of the world where the modern buildings look similar and the eventual purpose is them being a place of worship.
