: Whoa....this site calls Englemann spruce Sitka Spruce. A misnomer, or are
: they one and the same?!

It seems that every tree species has a wack of common names. Some of the common names are what the locals use and some were developed by marketers to sell a product previously poorly regarded.

Picea englemanii = Englemann spruce and/or white spruce in BC. Found at higher elevations in the Interior of BC, Alaska and Washington. The summary you quote is quite correct in that a lot of the white spruce is used in construction due to its tight grain and lack of twist/warp once kiln dried.

Picea sitchensis = sitka spruce. A coastal species between sea level and ~300m along the coasts of Wasington, BC, and Alaska.

So the moral of the story is that to be absolutely sure:
fall the tree yourself,
purchase by latin/scientific name only from reputable suppliers or
invest in a high powered microscope and educate yourself in wood identification.

grant