R. Gersion Appel explains the different approaches of the Chinukh and the Rambam to the Passover commandments in his newly republished book, A Philosophy of Mitzvot (pp. 171-172):
Apart from consideration of the patently rational elements and effects of a given mitzvah, the Hinnukh also considers certain emotional impulses, which are at times key factors in determining its meaning, as in his appraisal of the laws which hold a woman to be unclean in her menstrual period and following childbirth. He likewise takes note of the psychological impress of a mitzvah on a man’s character and mode of thought, as in his discussion of the effects of the specific laws pertaining to the Passover offerings.Learn more about the book here.
Click here to read moreThere is an evident disposition on the part of the Hinnukh to view the mitzvot symbolically, highlighting in particular their religious and nationalistic aspects. A striking example is his midrashic exposition of the prohibition of eating the sinew of the thigh vein, wherein he reflects upon its eschatological meaning and the deeper symbolism of the mitzvah with respect to the historical fate and destiny of the Jewish people. This is in marked contrast to the literalism of Maimonides in this instance who, while surely aware of the midrashic allusions regarding the mitzvah, nevertheless chooses to disregard them. A further example is to be found in their divergent approaches to the meaning of the laws of Passover. While both view these mitzvot initially in the role assigned to them in the Bible, as evoking a remembrance of Israel’s deliverance from Egyptian bondage, Maimonides proceeds to stress the moral lesson “that man ought to remember his evil days in his days of prosperity,” so that he will learn humility and gratitude to God, thus investing the Passover theme with a universal, ethical character. The Hinnukh, on the other hand, emphasizes the special significance of the Passover festival for the Jewish people, relative to its religious beliefs and national aspirations, underscoring its exclusive message to Israel regarding its freedom, its nobility, and its status as a kingdom of priests and a holy nation.
 Mitzvah 166. See chapt. VII.
 See Mitzvah 16.
 Mitzvah 3. See chapt. III.
 Moreh Nebukim III, 48.
 Ibid., III, 43.
 Cf. Mitzvot 7, 8, 13, 14, 15, 16, 21, 298.