Job search engines are similar to sites where you post job openings. The difference is more obvious to the job seeker because a job search site collects listings from multiple sites and allows users to view and pick from a larger pool of openings. Here are some examples;
These sites offer free job postings much like the free job posting sites. As before when using free resources, They all the same pitfalls of other free services. In other words you have little control over quality of candidates and the burden of screening in on you the recruiter so consider yourself warned!