It is unknown how Betas are differentiated from Alphas, but it is confirmed they are classified at young ages because Betas wolves, during pre-adolescence, leave the packs around the end of autumn to attend Alpha School for the whole winter. The Betas expectably return in spring after completing their training. Although they were Beta wolves and not Alpha Wolves, like Kate, the only Alpha wolf in Alpha school, Winston digilently taught them all well. It is unknown that Eve was also a teacher.
Unlike Omega Wolves, there was not a rule against mating between Alphas and Betas, before the rule against mating between Alphas and Omegas, was abolished.