Hi Bala,
I think both methods have some advantages and disadvantages. The disadvantage of one can be an advantage of the other.
The advantage of job posting is that you can get updated CVs of only interested candidates. You can assume that the candidate has read the profile and is interested in aspects such as designation, job profile, location, CTC, etc. So, it can be considered that the candidate is currently looking for a change and you can proceed accordingly. In the case of resume search, you cannot consider all of these factors.
I believe I have answered your query. If you have any doubts, feel free to revert back.