1. First of all, congratulations for getting selected for two different Central Government jobs.
2. So far as the two positions are concerned, it is needless to state that the job profiles of both the posts are entirely different. The post of Sub-Inspector in CISF is more 'physical' in nature. You will have to undergo rigorous physical training and handling of arms and ammunition. You will be posted in all parts of the country. Furthermore, the retirement age is less than 60 years if you don't become Assistant Commandant before reaching 54.
3. On the other hand, as a Station Master, you have to monitor train movement (Operating duty) and luggage/parcel booking (Commercial duty). It has an initial training of about 8 months of Operating and Commercial activities in the Zonal Training School of the Railway Zone where you will work. In a small station, where you will be initially posted (in all probability), you will have independent responsibility from the vey beginning. Although this is a transferable job, but your transfer will be confined to a particular Division within your Zone. You can rise upto Senior Station Superintendent (Grade-II). The retirement age is 60.
4. If you want to work in CISF or similar para-military organisations, you can try for the post of Assistant Commandant (Direct Recruit). If you want to work in Railway (line posting), you can try for the post ofTraffic Superintendent or Commercial Superintendent.
Beware! I question everything and everybody.