From observation:
Neurotypicals seem to need a high level of social interaction and struggle to concentrate or stay on task for long periods.
They enjoy talking about fictional storylines in soap operas as if the characters were real, and about the minutiae of celebrity’s lives. They will share and relive these revelations with exclamations of surprise as if experiencing it for the first time, and repeat similar with numerous people.
They can sit remarkably still for extended periods of time
They assume everyone’s minds work the way theirs do and seem to struggle to understand it even imagine different neurotypes.
They track and predict time quite accurately. This may be related to the consistent energy levels @UnimaginableWindBird mentioned.
They are very easily offended, and quick to attribute ill intention to any behaviour that transgresses their social norms.
They can be deeply suspicious and intolerant of perceived difference. But ironically do not like to be perceived as intolerant or discriminatory. So the same behaviour could elicit violence or understanding depending on whether they perceive it as aberrant or it has been labelled special needs.
They can be inconsistent in both their actions and opinions. And often believe things about themselves and others that are demonstrably untrue, even when the evidence has been pointed out.
They often form opinions by seeking consensus from their peers, rather than logic or reason, yet appear convinced that they are using logic, reason or the application of their own intelligence.