relevant names

Parshat Mishpatim

This week's shabbos table question on the parsha was (drum roll please..):

Near the end of the parsha the Torah starts talking about other types of laws than most of the parsha. It mentions shabbos, working 6 days and resting animals on 7th. Shemitta. The 3 main holidays. Then it gets into removing the seven nations from Eretz Yisrael.

When the Torah describes the three holidays, it does not call them by their main names, rather it calls them by alternative names. Hag Hamatzot, Hag Ha'Katzir, Hag Ha'Asif. Why? Why not call them by Pesach, Shavuot and Sukkot?

My 10 year old son thought maybe the Torah wants to teach us these alternate names.

I thought that maybe here the Torah is not really explaining the actual holidays. As a matter of fact the context seems to have moved into concentration on the land and agriculture. It says about shabbos that 6 days work and on 7th not work, so the animals will rest. Shemitta so the field will rest, Hag Hamtzot (this one it actually describes a little), Hag Ha'Katzir to bring the new fruit, Hag Ha'Asif to gather the grains. Throw out the goyim from the Land of Israel. etc..

Being that the main focus here seems to be on the land rather than on the actual details of the various holidays, I suggested that that is the reason the Torah used these alternative names - these names referencing the agricultural aspect of the holidays are more relevant than the more well-known names, at this point.