What is the difference between "Mitzvos Hashem", "Eidosav" and "Chukav"?
Ramban #1: "Mitzvos Hashem" refers to the majority of (general) Mitzvos, "Eidosav", to the testimonies - such as Pesach, Matzah and Sukah, and "Chukav", to the Mitzvos whose reasons we do not know. 1
Ramban #2: Refer to 6:20:1:1.
Seforno (on Pasuk 20): "Eidos" refers to the study in depth which serves as a factual testimony, and "Chukim" and "Mishpatim", to the fulfillment of the Mitzvos. 2
Ramban: We are obligated to keep all of them without questioning them, since we know for sure that they were given to us by Hashem - and it is not correct to serve Hashem with doubts, but to have faith in the Torah and in the prophets, which will lead to success. See Ramban DH 'u'Lekach Amar', who elaborates.
Presumably the Seforno will explain "Mitzvos" here like he explains "Mishpatim" there.