Is it just handle upgrades between omega boar/professional boar/premium boar ? or are the grades of boar hairs different in the knot ? please enlighten me.
Come on now ! There must be some smart people here who know the difference between plain Omega boar, Omega Professional boar, and Premium boar Omega shave brushes.
AFAIK the bristles are the same.
Some models are immediately softer (10066), others are more stiff (48/49) but they soften after few weeks of use.
Price depends on dimensions and handles. Professional are usually bigger, first price are smaller and have cheap plastic handles, Premium are bigger than first price and have wooden or resin handles.
See also:
I know Semogue has different grades (i.e. premium tops, extra tops, best) but I've never heard of grades of Omega brushes. I would think that the differences only come down to knot size, length, and density. Obviously the professional is meant for barbers (at a barbershop nearby my work, they use the Pro 49 for lathering up for the straight razor edging finish) and the premium are nicer handles. If you go to their website (I'm sure you have) they have the "entry" level ("first price"), regular, and professional.
The bristle in the "premium" brushes is different, finer and less densely-packed. I actually don't care for it as it doesn't provide enough backbone and takes a very long time to break in (i.e., split at the tips), if it ever does. I love the premium handles but have not had good luck with the knots. The bristle in the standard brushes is the same as in the Pros, but the Pros tend to be firmer initially in addition to being bigger. After five years, my 10066 and 10049 felt like two different sizes of the same brush, but in the end, my preference is simply for the big Pros.