premise: A man in a white shirt is riding a white scooter. hypothesis: A person is going to the store on their motorbike.
neutral: Sentence 1 specifically states a man which cannot infer person as a person can be either a man or  a woman.  Sentence one states the man is riding which does not infer to the is going to the store.  He can be riding to anywhere.  Their stated in sentence 2 cannot be inferred from sentence 1  as sentence 1 does not state who the owner/s are.  Motorbike stated in sentence 2 cannot be inferred from sentence 1 as sentence states a scooter not a motorbike.