while some people like to refer to it as white Walnut, it definitely carves and finishes like a completely different wood species.
Walnut is crisp and holds an edge well. it machines well, sands well, and takes an oil finish well. it has great figuring ... and it can be heavy
Butternut is significantly softer, and doesn't hold a sharp edge very well. it hand carves wonderfully, and is popular amongst woodcarvers for this reason. it doesn't machine or sand so well, as it likes to leave fiberous edges where you transition across the grain or have a sharp edge. a freshly sharpened card scraper will definitely be of use for all of the fine detailing prior to finishing. IME Butternut is also an oil finish sponge - I'd suggest a spray sealer and final finish. it has a non-interesting grain - but it can be quite light weight
I've used Butternut for a couple bodies, and have always enjoyed it's carving/cutting properties. I no longer offer it as a body wood option simply because Alder is so much better in every way. Locally, Alder is also cheaper than Butternut
all the best,
R