Performance Comparison Between datediff and date_format

Recently, there is a function that needs to query data in the database for a certain day, and the data time is in the timestamp format. In this way, when I query data, there are two options:

Select * From tuples where datediff (created_on, '2017-07-09 ') = 0
Select * From tuples where date_format (created_on, '% Y-% m-% D') = '2017-07-09'

The amount of data in the database is large, with more than 4 million entries. Compare the execution time

 

 

Showing rows 0-29 (175 total, query took0.0009Sec)
Showing rows 0-29 (175 total, query took0.0012Sec)

 

From the results, they are quite different, and both are acceptable. Datediff seems to be more efficient!