Some vehicles are not motorized or simply don't count as what is defined in a statute as a motor vehicle. For example a horsecart is a vehicle but not motorized. All Motor vehicles are vehicles but not the other way round. There are cases if a snowmobile is a motor vehicle for statutes, because lawnmowers aren't, but lawnmower tractors count as such in florida
An example from Germany: the StVO does only partially apply to horse carts like Beer-chariots that are a common sight in some areas in Germany (under § 24 I StVO) making it a vehicle but not a motor vehicle as it lacks a motor (§ 1 II StVG), resulting in the StVO not applying. However, if the horses damage another vehicle, the owner of the horse is liable as the owner of the animal under the BGB, not the driver of a motor vehicle.
Another example, where vehicles and other vehicles are not the same: MICHIGAN VEHICLE CODE Act 300 of 1949 Section 257.604 :
A person riding an animal or driving an animal-drawn vehicle upon a roadway shall be granted all of the rights and shall be subject to all the duties, criminal penalties, and civil sanctions applicable to the driver of a vehicle by this chapter, except those provisions of this chapter which by their very nature may not have application.