Human perception of the material reality is always indirect. This perception is mediated by the senses and incredibly limited to the tiniest scrap of the material reality, or to the extent that in the process of evolution was established by trial and error as necessary for the successful survival of an average human.
However in the case of the social reality, it is directly and in all its extent accessible to human perception. It is so because this kind of reality is fully generated and maintained by humans and their groups. In its entirety the social reality is stored in human brains.
The material reality is fully independent of human will, while on the contrary the social reality is fully dependent on humans.