Decibelmeters would encompass both "sound detector" modules as well as true instruments such as the "Gravity: Analog Sound Level Meter".

As "sound detector" would imply, the module is only really meant for some digital output where the user would be able to distinguish between the presence or absence of sound without a calibration phase. "Sound detectors" are easy to set apart from the rest due to the microphone that is a dead giveaway of the type of sensor and they are also relatively cheap.

True "decibelmeters" are more expensive, one such example being the "Gravity: Analog Sound Level Meter" that is able to tell the actual number of decibels with an error margin of , which is a great performance from hobbyist hardware at a low price.

Maybe when most people refer to "detecting sound", they just want to detect a sudden change in noise level, for which, the former cheaper variant would be great for all applications of the kind. However, if any remotely scientific measurements are to be performed, then a proper decibel meter would be more appropriate. Many other sensors of different types follow the same pattern, with a "cheap" solution, that would cover most of the cases, and then a more expensive variant that would actually confer meaningful and calibrated values.