Given the traffic and the poor state of Indian highways, buses are usually slower, less comfortable and less safe than trains. They however remain popular as the only cheap way of reaching places not on the rail network.
Both ordinary/service buses and luxury/express buses are available. The former are cheaper, more crowded, slower (multiple stops) and don't provide assured seating (no booking possible).
While the front part of the bus is generally reserved to ladies, eve teasing is unfortunately frequent in crowded buses.