Mono and stereo indicate the number of signals that are being used. Mono is just one signal, while the stereo is two signals. Mono stands for monographic or monaural sounds. Stereo stands for stereographic sound. Between the two, monographic is lower priced. The reason for this lower cost is that it is easier to record with and only requires a basic setup.
Stereographic sound takes more expertise in the technical field to record. There also uses different. Mono is used in AM stations, telephone communication, and talk shows done over radio. Stereo is used for FM radio stations and devices that play music.
The main difference between the two is the number of channels that are used. When you say mono, this means that there is only one channel that is being used. When you say stereo, this means that there is more than one available. There are times when the sound can be reproduced in different types of speakers, but the sound that will be reproduced will still come from just one source.
A lot of people say that mono may sound better than a stereo because all of the sounds are just concentrated on one item. The sound may be fuller, and you will be able to hear them more that way.