Guaranteed lead campaign means that the media will committed to give us the promised number of leads no matter how long the campaign will be. In rare cases, it is possible that a campaign will continue for more than six months if we haven't received the promised number of leads (in this case, adding an additional asset is highly recommended or if the client wants to end the campaign early, we can try to contact the media to end the campaign and they will only bill us based on the number of leads we received.
Guaranteed period campaign/ estimated leads campaign means that the campaign will only run for certain period of time (usually around 1 week - 3 months). In this case, there’s a chance that we might received 0 leads until the end of the campaign.