Are these two philosophies currently considered synonyms?
a belief that the world is causal and explanations
of the world are reducible to physics, chemistry
biochemistry & biology.
a belief that material substance being all there is
implies that volition and consciousness are the
result of material agency
Note: I'd change your question to "are these two perspectives synonymous?" It is a grammatical error and misnomer to consider either "a philosophy" as these are both world-views, not respect for obtaining wisdom (read: philosophy). It is etymological fact that philosophy translates from the Greek and through the Latin to "love of wisdom". This is distinct from "love of perspective upon the world". Wisdom obtains - in fact, requires - knowledge. If perspective could obtain knowledge then the poet's claims regarding a rainbow would have epistemic and ontological equivalence to Newton's prism. The former is an example of weltanschauung (an understanding of what is to you), the latter of verstehen (an understanding of what is)
A mechanistic perspective (emphasis my own):
"We ought then to regard the present state of the universe as the effect of its anterior state and as the cause of the one which is to follow. Given for one instant an intelligence which could comprehend all the forces by which nature is animated and the respective situation of the beings who compose it - an intelligence sufficiently vast to submit these data to analysis - it would embrace in the same formula the movements of the greatest bodies of the universe and those of the lightest atom; for it, nothing would be uncertain and the future, as the past, would be present to its eyes."
"A Philosophical Essay on Probabilities"
Pierre Simon, Marquis de LaPlace
As for their overlap, it depends on who is using the terms and how they are using them, so, yes, they can be synonymous but are not necessarily so. For a demonstration of the ways to use the term "materialism" as it relates to consciousness, watch this brief excerpt from a discussion between John Rogers Searle and Robert Lawrence Kuhn (transcription and emphasis my own):
"Well, it depends of course as we like to say, on how you define these terms. And if you define materialism as the view that matter exists in the sense that all of reality - all of material reality - is all the reality there is; and it has only a third person or objective ontology where it's equally accessible to any competent observer;... and the proposition that consciousness exists is the view that consciousness has a first-person ontology (that it's not part of a third person reality), then, of course, the existence of consciousness trivially would refute materialism... As always in philosophy you want to get behind the surface issues and see what's actually at stake here. The intelligent materialism is driven by the conviction that the account that we're getting of reality in subjects like physics and chemistry and molecular biology and evolutionary biology - that that ultimately gives us an account of how the world works and I think that's right. If that's materialism, then I'm a materialist, but I also think consciousness exists and it has an irreducible subjective ontology. It only exists when it's experienced by a human or an animal subject - by a conscious agent. But now if you put those two together then my task is to make the existence of consciousness in my sense - the real thing, not some ersatz or simulation, the real thing - consistent with what we know about how the world works. I claim that can be done. So consciousness does not refute my version of materialism, but it does refute certain traditional versions. What does that tell me? Let's get rid of this terminology of materialism and mentalism and so on and just describe the facts."