TO_date in oracle and postgres

Oracle:

To_date(number, text) it can take arguments of number and text and convert into a data 

eg:

to_date(20190606,YYYY)

returns 2019

Postgres:

To_date(text, text) here arguments should be of same data type or else it throws an error

eg:

To_date('20190606' , YYYY)

returns 2019