Maybe this helps ??
The Bible Student movement is a Millennialist[1] Restorationist Christian movement. It emerged from the teachings and ministry of Charles Taze Russell (1852–1916), also known as Pastor Russell, and his founding of the Zion's Watch Tower Tract Society in 1881. Members of the movement have variously referred to themselves as Bible Students, International Bible Students, Associated Bible Students, or Independent Bible Students.
I also understood the Berean Bible Students in Melbourne Aust. were a breakaway group from Russell according to a then Presiding Overseer in the 1960`s .