What is difference between a dead and a non-living thing?

Dead things are those who were once alive.

Nonliving thing were never alive (ex. rock, viruses...)

Living things are made up of units called cells, reproduce, are based on a universal genetic code (DNA & RNA), grow and develop, obtain and use materials and energy, respond to the environment, maintain a stable internal environmet and taken as a group, living things change over time.