I think there are many ways in which the words are used. And especially many ways in which people come to identify with their own conception of what either of the terms mean. The terms could simply be used to divide between those in moral conflict and those in moral agreement with the way things are happening / being done. It probably usually cuts across many subject domains. But trying to determine the similarities and distinctions between the two terms by speaking of groups of people (progressives, conservatives) instead of sets of ideas opens things up to a seriously wide range of complex
cultural and personal factors. I think the distinction between old and new is pretty serious today. Shouldn't be taken lightly. Rambling perhaps. To conclude, I personally try to avoid guiding my perspectives by identification with political labels. Work from the ground up, so to speak, from specific subjects. It requires you impossibly to be aware of very global affinties with concepts like (either) circles or spirals, rest or movement, the individual or the collective, because they prestructure your interpretation.

In addition: The Foucault Reader has proved useful already:

p. 46:
But if we are not to settle for the affirmation or the empty
dream of freedom, it seems, to me that this historico-critical attitude [***]
must also be an experimental one . I mean that this work
done at the limits of ourselves must, on the one hand, open up
a realm of historical inquiry and, on the other, put itself to the
test of reality, of contemporary reality, both to grasp the points
where change is possible and desirable, and to determine the
precise form this change should take . This means that the historical
ontology of ourselves must turn away from all projects
that claim to be global or radical. In fact we know from experience
that the claim to escape from the system of contemporary
reality so as to produce the overall programs of another society,
of another way of thinking, another culture, another vision of
the world, has led only to the return of the most dangerous
traditions.

***
This entails an obvious consequence: that criticism is no longer going to be practiced in the search for formal structures with universal value, but rather as a historical investigation into the events that have led us to constitute ourselves and to recognize ourselves as subjects of what we are doing, thinking,
saying.