Bangalore Metropolitan Transport Corporation [BMTC] — Coning in easy routs rather than fixed by bmtc

402D bus and 402B bus both comes in same routes where 402D should come in different route near 4thphase they also carry the easy routs if I ask the head in 4th phase main bus stop he tells me I had worked for 25 years u don't come and tell me but then y should they put 402D what is the difference between this 2 bus routes please this matter should be cleared