Behaviour is a translation of underlying brain structure, functions and neuronal networks in a given environmental setting. I don't think that you can just classify into "neurodivergent" and "neurotypical" only based on pure brain anatomy. We are all humans, so everyone has a human brain with slight individual variations. However, functional differences may occur more often and can be distinctive between groups (which network is more recruited for a certain type of task). These functional differences can translate in variations of performance and adaptation in a given setting. Functional brain imaging is generally used to explore and to search for explanations of observed behaviours, but is rarely used to classify or diagnose people. So, behavioural observations remain the main criteria for classification. "Neurotypical" and "neurodivergent" are however more of a social construction than a statistical.