In 2018, there is often confusion in articles regarding the difference between Internet-of-Things (IoT) and wireless sensor networks (WSN), often causing them to be blurred together. In this article we will go through some of the major differences between these two concepts and explain how they are, in fact, quite different alike.
We recommend reading our article What is IoT? before continuing.
In an IoT system, all of the sensors directly send their information to the internet. For example, a sensor may be used to monitor the temperature of a body of water. In this case, the data will be immediately or periodically sent directly to the internet, where a server can process the data and it can be interpreted on a front-end interface.
Conversely, in a WSN, there is no direct connection to the internet. Instead, the various sensors connect to some kind of router or central node. A person may then route the data from the router or central node as they see fit. That being said, an IoT system can utilize a wireless sensor network by communicating with its router to gather data.
You can think of a wireless sensor network as more of a group of sensors or "a big sensor" and less like a "competitor" or "rival" to the Internet-of-Things.
IoT exists at a higher level then WSN. In other words, WSN is often a technology used within an IoT system. A large collection of sensors, as in a mesh network, can be used to individually gather data and send data through a router to the internet in an IoT system.
It's also important to note that the term "wireless sensor network" is not nearly as encompassing as "the internet of things." WSN consists of a network of only wireless sensors. If the network was to include a wired sensor, it could no longer be labeled a "wireless sensor network." This is unlike IoT. Essentially any device that connects to the internet can be considered an IoT device. An "IoT system" can therefore be interpreted as a group of many IoT devices.
A fridge with the capability of sending temperature reading to the internet is unlikely to use a wireless sensor network but it IS an IoT device.
A large collection of sensors used to monitor precipitation on an acre of land is likely to be considered a "wireless sensor network" if in fact all the sensors are wireless. This system may or may not be connected to an IoT system.
Internet-of-Things - The connection of devices, generally not including smartphones, laptops, or PCs, to the internet. Additionally, as Business Insider puts it, "[a]ny stand-alone internet-connected device that can be monitored and/or controlled from a remote location is considered an IoT device." (source)
Wireless Sensor Network - A collection of wireless sensors that may or may not be connected to the internet.