The main difference between philosophy and sociology is that sociology has as its highest objective the description or explanation of the organization of the human crowd, whereas philosophy may (or not) produce an image of human assembly as one consequence, among many others, of the explication of a unique first principle which informs the whole reality.
Therefore sociology may be more "vraisemblable", but is paradoxically more myop.
Sociology looks more appealing and popular - it can explain you why you would better gift your nighbour with a box of chocolate rather than with a fridge (A.O. Hirschman, Felicità privata, Felicità pubblica), or why you tend to refer to your family rather than your boss to adress a problem if you are a conservative. Sociology gives you the feeling to catch the complexity of the mud you are into, in the social mess. To me, it has always secretely looked like the test results of a feminine magazine - it appeals to senses and curiosity, and sits between psychology and economics.