Platform as a Service (PaaS) brings the benefits that SaaS bought for applications, but over to the software development world. PaaS can be defined as a computing platform that allows the creation of web applications quickly and easily and without the complexity of buying and maintaining the software and infrastructure underneath it. PaaS is analogous to SaaS except that, rather than being software delivered over the web, it is a platform for the creation of software, delivered over the web.
A Thing is a physical object or even a piece of data, with a unique identifier and a group of properties like: location, temperature, speed, acceleration, altitude, weight, volume, pressure, value or any other variable that can be measured
The Internet of Things (IoT) is the network of physical objects (things) with unique identifiers and the ability to communicate and sense, as well as interact with their internal states and/or the external environment, without requiring human-to-human or human-to-computer interaction, by leveraging the Internet.
Big Data & Real time
For more on Big Data see here