Rosh Chodesh vs. Chol Hamoed

In his speech “הזכרת ראש חודש וחול המועד” in שיעורים לזכר אבא מרי ז"ל, Rav Soloveichik discusses Rosh Chodesh and how it is different at the most basic level from other Moadim.

קדושת היום

The central chakira that the Rav develops is whether the day has:

• Full Kedusha: the entire day has Kedusha, as is the case with the Holidays 
• Limited Kedusha: the day’s Kedusha is limited to its unique service in Beit Hamikdash, and for all other purposes it is a יום חול

Chol Hamoed, like Yom Tov, is a day of Full Kedusha:

קדושת חולו של מועד מקיפה הרבה דינים וחלותים, ובעצם קדושתו היא חפצא של קדושת חג הסוכות או חג הפסח. (הזכרת ר"ח וחוה"מ:ג)

Rosh Chodesh’s Kedusha, on the other hand, is limited to the Mussaf offering and therefore is limited only to Beit Hamikdash:

נקרא הוא יום מקודש אבל קדושתו תחומה ומוגבלת רק לקרבן מוסף. (הזכרת ר"ח וחוה"מ:ג)

אין קדושת היום של ר"ח מעלה ולא מורידה בגבולין. (הזכרת ר"ח וחוה"מ:ד)

Nafka Minot

The Rav goes on to discuss at length several Nafka Minot of this distinction(I’ll try to cover these in more detail in another post):

1. Tefilin on Chol Hamoed- Rav Chaim quoted as saying that chol hamoed has the same kedusha as chag, but with heter melacha. Therefore we don’t wear Tefilin on Chol Hamoed, while we do on Rosh Chodesh
2. Din Simcha- we say Hallel on days that have a mitzvah of Simcha as do the three Regalim. Rosh Chodesh actually has a limited din of simcha due to the minhag of treating it with a limited kedusha, so we say Hallel, but it has a lesser status
3. Shmonah Esre & Bircat Hamazon- The Rav ties a number of dinim in mentioning Rosh Chodesh/Chol Hamoed to the chakira of Kedushat Hayom. For instance, whether one is required to repeat a forgotten יעלה ויבוא