SOA is a lame enterprise approach, whereas microservices are a cool hacker approach.

If someone knows a non-flippant difference between SOA and microservices, i'd be interested to hear it.

Microservice architecture, as described, appears to be a SOA principles applied in a particular way (typically, to smaller units of functionality than are often considered with SOA), and with less baggage from association with WS-* standards (which, really, logically, aren't at all necessary to SOA, but have in many circles become so associated with it that its hard to say "SOA" without people thinking you mean "WS-*".)

SOA architectures are supposed to have formalized generic interfaces to services. EG: a standardized interface to a mailer, so you can pull out a mailer and replace it with another at will.

In practice, most "SOA" architectures are microservices.

Generally speaking, it's the lack of a linear service bus and orchestration.

In a 'traditional' SOA architecture, the workflow is defined as a linear progression from one state to another, where each 'service' mutates ( or not ) the state of the data.

Determining 'which' services are used/called in the service bus is typically defined in an orchestration.

They definitely have some similarities, however one thing to note about 'Architecture' is that it's often more about ways of thinking about a problem as much as it is about 'solving a specific problem'.

Another helpful comparison might be:

SOA is like GNU Hurd and Micro-Services are like Unix.

It does seem just like SOA to me, but maybe it implies even smaller services (that would seem to also imply more overhead due to extra requests, but maybe not)?