The answer is; In cellular respiration, chemical energy is transformed into mechanical energy; in photosynthesis, radiant energy is transformed into chemical energy.
Cellular respiration involves the breakdown of organic molecules (such as glucose) that store chemical energy in their chemical bonds. This energy is harnessed and converted to ATP (another chemical energy storage) ATP is then used to power cellular activities in the cell such as contraction of muscle fibers (this is transformation of chemical to mechanical energy).
Photosynthesis harnesses the radiant energy from the photos of sunlight to split water molecules into hydrogen and oxygen ions. The hydrogen is then used to reduce carbon dioxide to organic compounds such as glucose that store the harnessed energy in their chemical bonds.