In an ordinary train, you may have to shift compartments. This is like the path of action. You have to exert. Whereas in a through train, you do not have to change, it is a through carriage. This is the Bhakti path.
Indian trains are of good value but are most of the time overbooked.
If you know you want a rail pass, it may be prudent to buy it before you go to India from a travel agency. If you know your major itinerary well in advance, try to reserve seats from abroad through your local travel agent or the Indian Railways online reservation system . A new railway line linking Bangalore and Puttaparthi has been completed in the year 2000. Most cross-country trains run in 3 categories. Where available choose AC Sleeper or AC Chair for longer journeys.