You can see this type of difference in CSTM to LKO or GKP or BSP trains. While in Return journey very few tatkal seats. This is because while going to UP and Bihar there is heavy demand and as he start from mumbai the Railways think he has lot of money. while returning from UP and Bihar Railways thinks that UP and Bihari are poor people so they do not have money and so no tatkal seats . (very few compare to 280 to 330 tatkal seats )