There are many ways to categorize Things, one approach is to do so based on their connectivity and processing load:

Low Processing, Low Connectivity

A system is developed to do the following:

1. Hardware management (~ Low power computer)
2. Sensing, actuators data capture (~ actuators/sensors)
3. Gateway access (~communication)
4. Message handling (~communication)

Low Processing, High Connectivity

The same as above, with addition of a Cloud application interface

High Processing, How Connectivity

The same as above, with addition of

1. Application execution entity
2. Device management (managing both itself and others)
3. Data analytics
4. Data storage functional entity
5. Information sharing functional entity

The trend is toward:
Lowering size and power consumption, while increasing communication and processing power. And also standardization of communication.