The Railway Police Service (RPF) is responsible for the protection of passenger, railway properties, and security of the railway tracks and equipment. Besides, act as a connective link between the Government Railway Police/local police and the Railway administration.
The entire department is headed by Director General who is equivalent to that of the Additional Secretary. It consists of posts like, Assistant Commissioner, Inspector, Inspector (Prosecution), Sub-Inspector, Sub Inspector (Prosecution), Assistant Sub-Inspector, Head Constable and constable.
The eligibility criteria for the Railway Protection Force exam are the same as for other services. Candidates applying for the post of Assistant Commissioner must clear the civil services and gets allotment to the RPF service as per his rank; he has to go through specified training.
For more details on Group A service: https://www.civilserviceindia.com/Railway-Protection-Force.html
The RPF utilises a similar rank structure to the IPS (Indian Police Service). Non-gazetted ranks are the same as those used in the State Police Services. The job profile differs for each position.
Government Railway Police is a part of the State Police and is responsible for the maintenance of law and order and policing on the railways including running trains. The GRP has an almost identical organizational structure in each state. The Director General of Police of the State also controls the GRP, which is one of the several wings of the State Police. But Railway Protection Force has been created as an Armed Force of the Union under the R.P.F. Act 1957
It is placed under the Ministry of Railways and its members are deemed to be Railway Servants within the meaning of the Indian Railways Act 1989 and shall exercise the powers conferred on Railway Servants by or under that Act. RPF has been conferred with powers under the Railway Property (Unlawful Possession) Act 1966 to arrest, search, inquire and prosecute offenders of unlawful possession of Railway property. Being an Armed Force of the Union, RPF can also exercise the powers conferred on the Armed Forces of the Union.
For more details: http://www.indianrailways.gov.in/railwayboard/view_section.jsp?lang=0&id=0,1,304,366,533
RPF-Constable recruitment- June 2018