Primary key data type: integer vs identity

When I created the database I set primary key data types as integer; for
example:

Column | Type | Collation | Nullable | Default
--------------+-----------------------+-----------+----------+-------------
org_id | integer | | not null |
nextval('organizations_org_id_seq'::regclass)

I probably should have used the serial type, but didn't.

If it would be advisable for me to convert from integer to identity please
point me to the appropriate work flow.

Reading the CREATE TABLE pages in the manual did not give me sufficient
insights to appreciate the differences or indicate how to change the
column's data type.

Regards,

Rich