What are the differences between "Site" and "CONECT" in a PDB file

The CONECT section in a PDB file describes atomic connectivity.

The SITE section describes (among other characteristics), environments surrounding ligands present in the structure.

Now, how come not every atom in the CONECT section is described in the SITE section?

For example: 1a28.pdb

CONECT is for listing bonds, so that molecular graphics programs know how to draw the structure.
SITE is for annotation of interesting sites. Each listed SITE has a corresponding REMARK 800 that "details its significance". A graphical program may provide a menu with a list of all interesting sites for easy navigation.