In ALL Harvest Moon games, time is the most important game effecting game variable throughout the entire series. Each game has its own different kind of way time passes.
In the first game, time just went on, stopping when you go into town, but only lasted about a few minutes, with the great advantage of being able to do farm work and gathering at night because time basically stops and when you run out of stamina you can eat grapes or go to the spa.
Harvest Moon A Wonderful life brought into the system similar to the sims in which time passes one minute per second. Also AWL brought the feature of when you go to bed you sleep exactly 8 ingame hours. If you head to bed really early, you get to wake early. TOTT follows the Minute per second system, but not the 8 hours system. The minute per second system will also be featured im A New Begining.
In Friends of Mineral Town, and others I really can't think of, time goes by in 5 seconds per 10 minutes. That freaked me out at first but got used to it after awhile. This system is almost perfect making some days with extra time and some days rushing to get work done.