eg: Che Guevara
Revolutionist: A person who aligns himself in support of a revolution
eg: Members of the Boston Tea Party
The words are almost interchangable, but there is a slight difference.
In general, a revolutionary is the person behind a revolution, and a revolutionist is a member of a party or a movement.
For TLnet's purposes, it is my humble opinion that Bisu should be the revolutionary, unless we want to explicitly avoid adjective/noun confusion within the context of the sentence (revolutionary is adj/noun, revolutionist is noun only).