If you are P.R.China citizen,your H1-B visa is one time entry.You have to use your AP to come back to USA.Otherwise you have to wait and apply H1-B Visa in China
However,if you are Canada Citizen,you hold multiple entry H1-B Visa.You can come back to USA with H1-B Visa.You don't have to hold AP.
However,if you are Canada Citizen,you hold multiple entry H1-B Visa.You can come back to USA with H1-B Visa.You don't have to hold AP.