Fresh expressions of mission, or fresh expressions of church?
They are both. In the past we have had a 'come to us' approach to mission - 'let's set up church the way we like it and then invite others to join us'. We now realize that for the bulk of society this doesn't work. Many people ignore the Christian faith because the church seems so alien to them.
Fresh expressions are about a 'we'll come to you' approach to mission, which involves allowing new converts and the Spirit to shape the form of church - when, where and how it meets. As we follow the prompts and leading of the Spirit, we may start with a fresh expression of mission, but this will become a fresh expression of church as it develops the marks of church.
There clearly are many different fresh expressions of mission. These are new forms of outreach that aim to draw people into existing Christian communities. However if the aim is to be or create a new Christian community, the venture is more likely to be or become a fresh expression of church.