You'll run into a consistency problem when it comes to color designations.
A "olive" colored dubbing from Hareline will not be exactly the same color as a olive dubbing from Spirit River. In fact, they may be many shades apart.
BWO and Baetis are indeed the same bug but good luck finding an exact match for the body color! Around these parts, the natural bug has a light colored olive underbody and darker back. As the fish are below the dun, they see a light-colored body and not really any olive color I've found yet.
This is probably why as size 16-20 parachute Adams works as well as it does during a BWO hatch.
However, if you plan to use a soft hackle pattern to fish just under the surface to imitate a BWO emerger, a "martini olive" color is as good as any.
I'm going to state the obvious, not to be a smart Alec but maybe it will provide some ease of mind. If you get a drag free drift and are somewhere around the right size the color doesn't need to be too specific. Heck, size may not even play that big a part if your drift is right. I've seen some seriously "educated" fish in Cheeseman Canyon CO slam a floating cigarette butt as it floated down stream from some donghead upstream. Blew my mind as I was matching the midge hatch! . While sight fishing seeing them come up to my fly and reject it only to hit a cigarette butt. That thing floated drift free though.
As noted above, Blue Winged Olives are mayflies of a complex of genera including the genus Baetis (pronounced, by the way, Bee-tiss). This complex includes a number of genera, including Baetis, Accentrella, Diphetor and Plauditus and there are at least 26 western species. Common species include B. tricaudatus, B. bicaudatus, A.turbida and D.hageni.
Typically nymphs are some shade of olive though they may range from tan to dark brown and are 1/8 to 1/2 inch long. Duns range from tan to olive brown or gray (colors may vary with species and habitat) with pale to dark slate-gray ("blue") wings and are best tied in sizes 16-24. Members of this complex hatch year-round, most prolifically in spring (February-April) and fall (September-October).
Since mayflies of this complex are found in almost all of the west's moving waters and hatch in good numbers throughout the year, they are one of the most important flies for the angler to imitate.