what is the difference between L'visa for tourists and 72-hour visa free policy in China??

L type one is issued to all foreigners who plan to visit PRC (Some nationals might can't apply for individual type L). The duration period is usually at least 30 days. However, 72 hours free transit is for people from certain 45 countries. It just allows them to stay for 3 days in PRC and the applicants can't leave the city during their stay in PRC.