2. The patent in China is the principle of first application, and whoever applies first will have the patent right. As you mentioned, B can get the patent right, but A can enjoy the right of first use, that is, it can continue production but not expand the original production scale.
3. The difference between invention and utility model is that
A protects different objects, while invention protects products and methods, while utility model only protects products;
B the review process is different, and the invention has to go through the preliminary examination and the actual examination, while the utility model only has the preliminary examination but not the actual examination;
C according to b, the stability of invention and utility model patents is different;
D protection period is different, 2 years for invention and 1 years for utility model;
E the application fee and annual fee are different.