As I read, there are two patterns to define one microservice, by [business capability](http://microservices.io/patterns/decomposition/decompose-by-business-capability.html) and by [subdomain](http://microservices.io/patterns/decomposition/decompose-by-subdomain.html). But I still find it very ambiguous. I get confused how these two patterns differentiate from each other. Both of them revolve around activities involving an area of business logic. All of components in each service are small enough to get packaged with each other without affecting other services. Could anyone please give me a further explanation about these two?