Aspects are the distances between planets that make a difference in their expressions. 90 degrees between two planets is considered to be a square. However, a square has a different expression if it is waxing (growing) or waning (releasing). This is one of the finer points of astrological interpretation. This fascinating and fun lecture by Georgia (presented for the remarkable Astrology Hub program in 2021) shows you these differences.
Next time you read a chart, you will see it with completely new eyes! Enjoy!