Definition
Topocentric means referred to a point on Earth's surface (the observer). Parallax — the shift in apparent position due to the observer not being at Earth's centre — matters most for the Moon and nearby planets.
vs geocentric
Geocentric coordinates use Earth's centre. The difference (topocentric − geocentric) is the parallax correction. For stars it is negligible; for the Moon it can exceed 1° in horizontal coordinates.
