"Each and Every Month, and Each and Every Shabbat"

Parashat Pinchas and Parasht Emor include Shabbat and Rosh Hodesh in the list of festivals. Shabbat and Rosh Hodesh are also appointed a special Musaf sacrifice, just like other festivals. Apparently, Shabbat should be considered a sanctified day and a day of rest despite the fact that technically it is not a holiday. The unique Musaf sacrifice offered on Shabbat indicates a unique status among the festivals. In contrast, Rosh Hodesh is not considered "Mikra Kodesh" - a sanctified day - but is nonetheless included in the list of festivals. The status of Rosh Hodesh is therefore somewhere between that of Shabbat and a regular day.