I wonder what the difference is between "sciences sociales" and "sciences de la société".
The ngram is a valuable tool, but in this case it may not paint the whole picture. This is rather subtle.
As I see in contemporary usage, while "sciences sociales" has been a standard form of use over the past 50 years, in the past 15 years "sciences de la société" appears to be the more PC usage in the world of education at least, possibly in a wider circle.
It may be a form of "hexagonal," i.e. jargon-like French that makes you sound more professional at the cost of simplicity and elegance -- or it may be an inflected use due to sociopolitical implications of the earlier "sciences sociales" since "social" may also carry the connotation of "assisted" ("assurances sociales," "aide sociale" etc.).
So, for a writer who aims at the official world of education, it is possible that "sciences de la société" may be a more appropriate wording if the audience is an official audience (for instance a textbook that needs to be approved, or an article submitted to an education publication). It may also allow the writer to use the appropriate "code" that shows that she/he belongs to the right stratum or initiates' circle.
If you look at the ngram, you will see that "sciences de la société" only appears in the past 15-20 years. Its use may also have leveled off over the past 5-10 years. I am not fully current on its use in the education world since 2010, but, browsing official education sites right now, I still see it prominently displayed in the naming of many university programs.
As for me, I dislike hexagonal and would use "sciences sociales" unless I had a very good reason to do otherwise.
There is a strong difference in usage, Sciences sociales are well know academic fields of study while Sciences de la société, while not unheard, is rarely used, often in the GHSS acronym, Géographie, Histoire et Sciences de la société used to name a French universities UFR (Unité de formation et de recherche).
Ngram shows about one hundred times less Sciences de la société than Sciences sociales and digging the results show many false positives.
There is no difference :
socialesis an adjective meaning related to society
de la sociétéis another form which demonstrates the possessive form like the English
of the society.
Il n'y a aucune différence:
socialesest un adjectif signifiant relatif à la société l'équivalent en anglais est
de la sociétéest une autre forme qui démontre la possession comme en anglais
of the society.