Both Semax and Selank are synthetic peptides. Semax is a synthetic analog for ACTH and Selank is a synthetic derivative of tuftin. In addition to the effect on cognition, Semax is known mostly for its neurotropic properties and Selank is involved in the modulation of the immune system and anxiety.

Both Semax and Selank are synthetic peptides with nootropic properties (increasing cognitive functions). However, they differ in their effects and uses. Semax is primarily used for its cognitive-enhancing effects, while Selank is known for its anti-anxiety effects. Despite their differences, both peptides are used in neurology and psychiatry for their neuroprotective properties.