sql query execution using exists and IN

Question

SELECT * FROM FAMILY_DETAILS WHERE EXISTS(SELECT EMPLOYEE_ID FROM EMPLOYEE_MASTER WHERE EMPLOYEE_ID='EMP001')

SELECT * FROM FAMILY_DETAILS WHERE EMPLOYEE_ID IN(SELECT EMPLOYEE_ID FROM EMPLOYEE_MASTER WHERE EMPLOYEE_ID='EMP001')

I have these two queries in sql server 2008 R2. Both will give same results. Actually from these above queries output is only two rows, But in case if i have large number of records in that scenario Which one is better to use? and why?