A Terry Stop is basically when the police stop and detain someone walking or riding a bike etc.
The Terry Stop in the United States law allows the police to briefly detain a person based on reasonable suspicion of involvement in criminal activity and is usually done when the person is walking or riding a bicycle etc.
When someone is stopped by the police in a vehicle that is known as a traffic stop and they can stop you for traffic violations or if they believe you're involved in a crime or if you have a tail light out etc.
But a Terry Stop is for reasonable suspicion of the person is involved in a crime or other criminal activity.
A traffic stop can seem like a Terry Stop but they are different when it comes to law.
If you're pulled over in a vehicle by a cop and then go to court then the court will reference that as a Traffic Stop and not a Terry Stop.
If you're stopped on foot or a bicycle then the courts will refer to that as a Terry Stop.