How to compare two arrays and pick only the non matching elements In postgres

Question

How can I pick only the non matching elements between two arrays.

Example:

base_array [12,3,5,7,8]
temp_array [3,7,8]

So here I wan

Answer 1

select array_agg(elements)
from (
  select unnest(array[12,3,5,7,8])
  except
  select unnest(array[3,7,8])
) t (elements)