Dear student,
Autotrophs are organisms that can produce their own food (organic carbon compounds) from inorganic carbon sources.
Heterotrophs can not synthesize their own food , they get their reduced carbon from other organisms.
Similarities:
Both autotrophs and heterotrophs depends on light and chemicals for energy production.
Light as energy source:
Photo autotrophs use sun light to convert water and carbon dioxide into glucose.
Photo heterotrophs attain the carbon from carbohydrates, fatty acids and alcohol in the presence of light.
Chemicals as energy source:
Chemo autotrophs use CO2 as the main carbon source.
Chemo heterotrophs get their energy from preformed organic compounds.
Regards.