Heh Yeah, the NT syndrome web page has made me chuckle more than once. The sarcastic humor of it is that we're treated like the way we do things is pathological; therefore, let's write about typical people the same way, and see how silly it looks!
Neurotypical started out by meaning "non-autistic", but nowadays it means "having a neurological setup in the average range". The word "neurodiverse" is the opposite, meaning people who are not in the average range, including autistics as well as every other non-typical neurological configuration, like ADHD, traumatic brain injuries, or cerebral palsy. In some meanings of the word it also includes non-diagnosable things like simple synesthesia or giftedness.
The language gets kind of complex, but here we go:
Neurotypical: Someone who has neurology in the average range.
Neurodiverse: Someone who has atypical neurology, usually diagnosable as having some disorder, but may not be diagnosable because the atypical neurology does not cause impairment.
Autistic: Someone who can be diagnosed with an autism spectrum disorder.
Non-autistic: Someone who doesn't have autism. Includes neurodiverse people who do not have autism.
Subclinical Autistic Traits OR Broader Autism Phenotype: Someone who has autistic traits, but who cannot be diagnosed because he has no significant impairment. BAP refers specifically to relatives of autistic people who show autistic traits.
Culturally Autistic: Someone who identifies as part of the autistic community. May be diagnosable, may have been diagnosable in the past but "lost" the diagnosis, or may have subclinical autistic traits.
Spectrum Cousin: Someone who has a diagnosis which is not autism, but is closely related to autism and shares many traits with autism, such as ADHD, learning disabilities, Fragile X, sensory integration disorder, etc.
Hopefully that helps.