A Solar Return is an exact moment when the Sun returns precisely to birth position after completing a full orbit rotation through the zodiac. Almost always the date that the Sun returns to its natal position is the same day as the birthday, or one day earlier, or one day later. In very rare circumstances, it could occur 2 days earlier later.
Lunar Return is based on the Moon’s return to its natal position about once a month (approximately every 27 1/2 days). A chart calculated for the time the Moon returns to its natal position is the Lunar Return chart and it gives indications for the coming month.