[Tiva]

'Groups of people' is code for a religious group or cultural group in many things that I deal with I took it as such, sorry for the assumption.

Anthropology is the study of humans, past and present their culture and all aspects for what they do while striving to understand what they do or did.

Philosophy is the study of general and fundamental problems, such as those connected with reality, existence, knowledge, values, reason, mind, and language.

Those are taken from Wikipedia and my old Anthro textbook.
All people in one aspect is Philosophy, a group of people in all aspects is Anthropology. Best way to explain it.