For reference the Druzhina was a group of men in early Rus who helped the prince administering his principalit. The individual member of druzhina was known as druzhinniki and the first members of druzhina were actually Norse warriors (varangians), they were eventually joined by members of the local Slavic aristocracy and adventurers . The weapons they used varied from Swords and Axes to Maces. They were trained warriors but not quite on par with the Feudal Knights which trained from a young age and almost constantly.
In summary Druzhina is a group of warriors in service to a lord. Boyars on the other hand were not necessarily all warriors but if they were they were mostly better equipped and way better trained.