well sleeper usually means the seats are more like pull out seats which stretches like a bed and there will be a bed on the top on top of your head and slumbrette i guess would be some kind of push back seats,,but still get it confirmed

“slumberette,” a comfy 135-degree reclining seat
sleeper means on the top of seat mini bed are facilated like train 2 tair or 3 tair

By Bus — If you want to travel to Goa but all trains and flights are full, or if you want to save on airfare, your next-best option is a bus from Mumbai, Pune, Hyderabad, Bangalore, or Mangalore. Numerous overnight buses leave from Mumbai (near Metro Cinema-Fashion St.) every day at 7pm; try to book an air-conditioned bus. Preferably, this should be a sleeper, not advisable if you are traveling alone, as you will sleep beside a stranger; in this case, buy two tickets for Rs 800 to Rs 1,000 ($11-$23). Or you can opt for a semi-sleeper or “slumberette,” a comfy 135-degree reclining seat for Rs 500 to Rs 800 ($11-$18), depending on the season and quality of the bus. Some companies provide blankets and bottled water.