In my talk I will discuss two types of dark matter scenarios giving rise to a suppression of the power spectrum at small scales. I will focus on the case of warm dark matter and compare it to the case of dark matter interacting with light degrees of freedom. I will discuss how their properties can affect astrophysics probes as well as cosmological probes. In particular, I will discuss how 21 cm Cosmology might help to distinguish between these "non-Cold" dark matter scenarios.