Although the below terms are often used interchangeably and loosely, they have the following subtle differences technically.
 福报 = Blessed (福) rewards (报) or blessings, created by  good karma (善业).
 善业 = Good karma, created by body, speech and mind (身口意) with self-attachment (我执), leading to better life and better rebirth.
 功德 = Meritorious virtues = merits (功) + virtues (德) =  pure karma (净业), created by body speech and mind without self-attachment, leading to Pure Land (净土) and liberation (解脱).
 福德 = Blessed virtues =  blessed rewards (福报), created by  good karma (善业) +  meritorious virtues (功德), created by  pure karma (净业).
 净业 = Pure karma also refers to karma to facilitate birth in Pure Land, most directly by mindfulness of Buddha with Faith and Aspiration (信愿念佛).