There is subtle structural different between type A and type B atomizer head:
If you put A type atomizer head into B type atomizer body, it may cause a little leakage.
If you put B type atomizer head into A type atomizer body, it may cause a little burning taste.
Through test, in order to reach the best effect, we recommend you not to mix type A and type B pack in use.
ETA: Type B are laser etched.