What is the performance difference distinct vs group by SQL command

Don't use distinct command.It performance way is slow. group by command performance very high compare to distinct command.Please see the real time difference in the below example query.

1) select count(*) from (select distinct contact_id from contacts_lists) a;

 count
 65474

 1 row(s)

 Total runtime: 40,800.186 ms

2) select count(*) from (select contact_id from contacts_lists group by contact_id) a;

 count
 65474

 1 row(s)

 Total runtime: 32,302.381 ms