Ashley Foster, who is from High Green, and Jonathan Bowling, who is from the Fox Hill area of north Sheffield, were both arrested earlier this week.
They will remain in police custody until they appear in court in the morning.
Grandfather Mr Greaves, 68, was a lay preacher and his death shocked the community where he lived.
He lived just a few hundred yards from where he was attacked.
After the incident he was taken to hospital with severe injuries to his head but did not survive.
More than 50 police officers were drafted into the inquiry and detectives made a series of appeals for help from the community.
More top news
Sixteen Colombian police officers have been killed after their helicopter crashed while searching for the nation's most-wanted drug lord.
Two men have been arrested after a methamphetamine lab was discovered inside a Taco Bell restaurant in the US.
The Labour leadership contender has vowed to renationalise Britain's railway network "line-by-line" if he becomes prime minister.