Because a Martian sol is slightly longer than a Terran day, the calendars do not line up. Therefore, the sols of the week were given new names, similar to their Terran counterparts.
Because a Martian rev is much longer than a Terran year, there are many more months. Most months are 30-31 days (except Ferruary); this is in keeping with Terran convention as the Martian moon with the longest phase is Harmonia at 13 days. The calendar follows a similar layout to the Gregorian calendar. A Martian rev is 22 months long, and every year divisible by five is a leap year in which 3 extra days are added to Ferruary.