They could have been brothers.
Samuel and his family lived in Coshocton County, Ohio in 1850. Here is what his son James stated in his Civil War Pension papers: "In the fall of 1858, I had lived in but left Columbus, Bartholomew, Indiana. Then moved to Matoon, Coles County, Illinois."
Might that have been to live near Uncle John, after his father Samuel died? Along with him, came James' mother, brother (also named Samuel) and three sisters.