The difference between the public transport and the commercial transport:
the appearance – commercial buses which look in the same way as the regular ones have the “K” letter in front of the number and the minibuses are always the commercial buses;
the differences in stops – the public transport stops only at the stops of public transport, the commercial transport – anywhere on the route upon the request (the polite form of request is «остановите, пожалуйста» you can see it on the section «No language barrier»);
the speed of driving is faster,
the fare is more expensive (35 rubles and more if you are going to the suburbs).
The fare is paid directly to the driver. 2 people who sit behind the driver usually pass the money (the cash and the change) to the driver.
If you use the commercial transport, say or show the address in advance – the commercial buses can miss the stops, so you will be misleaded when to get out.
If you are standing not at the 1st stop of the transport you should hitch-hike it.
The buses with the same number but the absence or presence of the “K” letter have different routes, be attentive!