Rabbi Yochanan states (Kiddushin 33a) : They stood before those bringing the bikkurim, but not before Torah scholars.
Rabbi Yosi bar Avin explains: Come and see how precious a mitzvah is in its proper time, for the craftsmen would rise before those bringing the bikkurim, but not before Torah scholars.
The Gemora asks: Perhaps they would only rise before those bringing bikkurim (but not for an ordinary mitzvah) because if not, they will not bring the bikkurim in the future (for they will think that the people living in Yerushalayim have no respect for them).
The Pnei Yehoshua writes that although it is obvious that the studying of Torah is greater than the performance of mitzvos, and even a mitzvah which has a set time, nevertheless, here, those that are performing a mitzvah are greater than Torah scholars. This is because it is quite possible that the Torah scholar is not engrossed in learning as he is walking.
The Chasam Sofer asks: And is a Torah scholar not occupied in performing mitzvos as he is walking? The Gemora Brochos states that a Torah scholar does not walk even four amos without thinking in Torah!? Why shouldn’t they stand before him?
He answers that according to halachah, thinking in learning is not equivalent to studying out loud, and therefore it is not in the same category as one who is performing a mitzvah while he is walking.
The Noda BeYehudah answers that a mitzvah which does not apply every day is more significant than the mitzvah of studying Torah, which applies every day.