What is the relationship between $\mathsf{APX}$ and $\mathsf{MaxSNP}$ classes? My understanding of these classes is a really fuzzy. The more I am trying to read the more I am getting confused. Can anyone help me understand the relationship between these classes. More precisely, is $\mathsf{MaxSNP} = \mathsf{APX}$  or $\mathsf{MaxSNP} \subset\mathsf{APX}$? 

Thanks a lot in advance. :)
See the following paper by Khanna etal on syntactic vs computational views of approximability. MaxSNP is a syntactic class while APX is a computational class. dl.acm.org/citation.cfm?id=298507

Made comment into answer as per Suresh's request.