Although they are very similar, the only thing that have common is the same plant species. [36]

- Chlorella is a green unicellular alga with a core
- Spirulina is a blue-green, multicellular cyanobacteria without a core
- Spirulina can reach up to 100 times the size of Chlorella
- while Chlorella has a round shape, Spirulina is spiral
- both of these plants are good sources of nucleic acids, but Chlorella contains almost twice as much as Spirulina per gram
- Chlorella has a hard and indigestible wall and therefore requires additional mechanical treatment before consumption. This process is also reflected in the resulting Chlorella price, which is more expensive than Spirulina
- Spirulina has a digestible wall
- Spirulina and Chlorella also differ in nutrient content – Spirulina has more essential amino acids, iron, protein, vitamin B, C, D and E
- Chlorella does not have as much iron, protein and gamma-linolenic acid as Spirulina
- Chlorella contains almost twice the amount of chlorophyll compared to Spirulina