Did some research on this few weeks ago for this very reason. ERC is actually a Juniper and Western is a Thuja (as is the giant arborvitae). Neither are true "cedars" or cedrus.
Both are good for lumber, ERC is lighter and takes a long time to rot. Westerns grow to be very large and market for lumber on those in pacific NW is big indrusty.
Id imagine people stay away from ERC cause they are such a pain to limb out for timber harvest. Though there are lots of buyers in the Ozark Mountains of S mo and Arkansas