Dear,
Recruitment means hiring candidates for the present and/or future vacancies in your organization. Recruitment may be done from various sources via advertisements, job portals like naukri.com, consultants, employee references, etc.
Staffing means fitting the right candidate at the right job. It includes matching the skills and knowledge of the employees with the requirements of the job, i.e., job specification and job description. Staffing is the next step after recruitment and selection and may be based on performance in various tests, interviews, etc.
Outsourcing means getting any type of service in your business from some external source, like getting payrolls prepared for your employees by some chartered accountants (who are not working in your company and are not on your payrolls).
Regards, Ruchi