After reading it, this is not a duplicate of Explicit vs Implicit SQL Joins. The answer may be related (or even the same) but the question is diffe
In SQL, the 'WHERE' and 'ON' clause,are kind of Conditional Statemants, but the major difference between them are, the 'Where' Clause is used in Select/Update Statements for specifying the Conditions, whereas the 'ON' Clause is used in Joins, where it verifies or checks if the Records are Matched in the target and source tables, before the Tables are Joined
For Example: - 'WHERE'
SELECT * FROM employee WHERE employee_id=101
For Example: - 'ON'
There are two tables employee and employee_details, the matching columns are employee_id.
SELECT * FROM employee
INNER JOIN employee_details
ON employee.employee_id = employee_details.employee_id
Hope I have answered your Question. Revert for any clarifications.