Chlorella vulgaris and Chlorella pyrenoidosa are two common types of chlorella. They differ in their chloroplast structure, cell wall thickness, and nutritional profile. Pyrenoidosa has a pyrenoid, which boosts its photosynthesis and vitamin production. It also has a thicker cell wall, which may make it better at binding to heavy metals and toxins. Vulgaris has a thinner cell wall, which may make it more digestible and protein-rich.