The free Microservices vs SOA book gives an excellent run down of the difference between microservices and SOA. It's really useful to have this in mind when having any conversation about microservices.
"One of the fundamental concepts to remember is that microservices architecture is a share-as-little-as-possible architecture pattern that places a heavy emphasis on the concept of a bounded context, whereas SOA is a share-as-much-as-possible architecture pattern that places heavy emphasis on abstraction and business functionality reuse."
http://www.oreilly.com/programming/free/microservices-vs-ser...
"One of the fundamental concepts to remember is that microservices architecture is a share-as-little-as-possible architecture pattern that places a heavy emphasis on the concept of a bounded context, whereas SOA is a share-as-much-as-possible architecture pattern that places heavy emphasis on abstraction and business functionality reuse."