Photosynthesis is the process of creating or producing energy from sunlight. This is a unique process employed by plants and oxygenic bacteria like Cyanophyta or Cyanobacteria. It is the chlorophyll, the green pigment in plants, that is primarily responsible for this process.
On the other hand, respiration occurs in most other living beings. The body's respiratory system allows it to obtain oxygen from the surrounding air.
The difference is that plants need sunlight to photosynthesize while other living creatures do not need it for respiration.
Also, plants take in carbon dioxide and expel oxygen in photosynthesis. Meanwhile, other living creatures take in oxygen and expel carbon dioxide. Thus, establishing an important mutual relationship between the two processes.