I have two polygon datasets: electoral districts and postal code areas. I'm performing a spatial join to see which postal code areas are completely within a district (the area can touch the borders, but doesn't cross them; i.e. not situated in 2+ districts).
The way I see it I can do it two ways:
(1) Districts as target features, postal code areas as join features with a Contains Clementini match option
(2) Postal code areas as target features, districts as join features with a Within Clementini match option
I assume these are the same thing. Yet I have ran both and they yield different results.
Theoretically: why am I getting different results? And which way is deemed "more correct"? Thanks for your input in advance!