I have to suggest that the word "anarcho-socialism" could be considered a bad case of redundancy in a composed word. This mainly since all anarchism can be considered a socialist position (including individualist anarchism) since all anarchism opposes wage labour and class stratification as obvious examples of hierarchical forms (the main things anarchism opposes) and also main features of the capitalist system (the main things socialism critiques). It could be for this reason that the word anarcho-socialism has not been used too frequently within anarchist contexts and so it makes me wonder ¿where did you read or heard this word?
In the only sense that the word "anarcho-socialism" can have some sense is if it points out to a particular anarchist tendency which emphasizes and concentrates on economics and social class issues as these things could be said to be the main characteristics of socialism in general. The word "Social anarchism" has been used more frequently for this though and so it is made up of the main anarchist economic theories of collectivist anarchism, anarcho-communism and anarcho-syndicalism. So in this way things like anarcho-feminism or queer anarchism or green anarchism could be said to have less of a class and economic emphasis and so more of a concern on gender, identity discrimination and ecologist focus. Other tendencies with different emphasis are for example synthesis anarchism, insurrectionary anarchism and platformism which focus more on forms of anarchist organization and anarchist strategy rather than on economic systems. Nevertheless all of these tendencies could also be said to be "socialist" since they also will oppose class hierarchy as well as sexism or homophobia even though their emphasis might be different.
Anarcho-communism on the other hand is an entire school of thought and tendency within anarchism mainly represented in the writings of Peter Kropotkin and Errico Malatesta. http://en.wikipedia.org/wiki/Anarcho-communism