From a very basic definition, we should also say that class struggle is social antagonism between classes.
Social war being in the same time a more general antagonism, against politcal parties, authority, the police, all kind of oppressions, and (so) a higher level of intensity in social conflictuality.
The fact is that now a day it's often only used as a concept to say "the struggle against all authority". The problem being that to many anarchists and autonomous from the 70s and the 80s, the term defined a kind of situation in which a certain level of intensity in social antagonism was rised.
Those who defend the idea that there is still a certain intensity level of antagonism in society, define a large scale of anonymous and both anarchist and non-anarchist actions and social conflictuality to put in evidence the fact that there is actually a social war.
Some others, including me, think that this is an interesting approach of the social background, but rather talk about a "low intensity" social war (if you use it to describe the social background, and not only as an anarchist concept) to discribe the actual situation (in france, for instance), as there always were violent conflictuality and class struggle clashes since the world is what it is. Capitalism, the State, the Kyriarchy of all dominations and oppressions.
Let's say that medium intensity would be when the general consensus and the normal order of things is broken, and high intensity would be such thing as the "insurrectionary" or "revolutionary" situation in terms of social war.
Of course, these terms aren't "water-tight", and subjective, and depend on contingent events.
But it's seems an interesting accuracy to me.