Hello ,
Both are different type of contraceptive. Unwanted 72 is emergency contraceptive. You can take it in case of unprotected intercourse or when regular contraceptive fails , like condom ruptured.
Ovral l is to be taken cyclically, start from day 4/5 th of your cycle, take daily , when you complete the entire pack, you will get periods.
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You can compare both , as both are different methods of contraceptive. I would advise you to take ovral l regularly for contraception . And unwanted 72 , only in case of emergency or failure of regular contraceptive, not for regular use after intercourse.