The difference between Aviane (Alesse) in a 21-day pack and a 28-day pack is that the 21-day pack contains 21 active pills (orange pills) only, while the 28-day pack contains the same 21 active pills plus 7 inactive pills (green pills). The extra 7 pills in the 28-day pack are there to help women keep track of their pill-taking schedule during the week without active pills. Both the 21-day and 28-day packs are equally effective in terms of hormone content. If a pill is missed, it is important to take it within 24 hours and continue taking the pills at the same time each day to maintain contraceptive effectiveness.