Please visit Part-1 before reading this ....
The Sleeper class is slightly more somber and conversations and participants are a bit more widely represented. The conversations are a shade more intellectual less noisy and the seat adjustments are the prerogative of the TTE; the governmental interference starts creeping in bringing in with it the baggage of discretion, corruption etc.. It is the class of the classless society.
The new entrant ,the AC3 Tier has been the latest favourite of both the Railways and the upwardly mobile among the middle class. The clientele is relatively less widely represented but still has an aura of openness and social comfort. It is not uncommon for some one even among those who can afford a higher class insisting on travel by AC 3 Tier or sleeper over 2A or H class just for the privilege of a conversation in a long journey.
The AC 2 tier; hah you have nearly arrived in life or think so and with it come the qualities of reticence and reservedness. You tend to read more than you speak and flaunt the intellect by choosing to read a Herman Hesse or Robin Cook over PG Wodehouse or Hardly Chase. It is quite difficult to spot anyone reading a Regional Language book or News paper. Yes there is an occasional bit of conversation and discussions from Socially and intellectually equals. The only exception may be trains passing over Howrah where loud conversations (in Bengali) are common preventing any chances of sleeping in daytime and proving Amratya Sen right. The irony is that very few travel this class paying from their purses. The business class starts here.
The real business class is the AC first class abbreviated the H Class, where people are sub compartmentalized with doors to shut and lock. This is the only class where the TTE tends to call the customer Sirand the front office training shows up quite often. The attendant spreads the bed and you are sure of getting a wake up call in time. A class best suited to travel with a family of 4 or your best friend at a princely price.
What ever may be the class you may prefer to travel, a travel by an IR train is a class apart.