Site; A place, as in “Bob went to the job site” or “Joe spent a lot of time at the Boomershoot site this last weekend.”
Sight; Generally, vision or something you see, as in “Bob lost his sight in one eye while on the job site last year.” In the case particular to firearms; the aiming apparatus (or a part thereof, e.g. “front sight” or “rear sight”) of a firearm as in, “Bob lost the front sight from his rifle at the Boomershoot site last weekend.”
With the release of this secret knowledge, you are now well ahead of many firearms enthusiasts in the highly specialized and esoteric field of study that is firearms nomenclature. You’re welcome.