Rhydon's stats are 105/130/120/45/45/40 (HP, Atk, Def, SpA, SpD, Speed)
Rhypherior's stats are 115/140/130/55/55/40 (Same format).
They are both physically based (in offense and defense) and Rhypherior's stats are far superior in every sense (apart from speed :P) (for gods sake, Rhyperior is the evolved form of Rhydon xD)
They also have the same typing of Ground/Rock, and Rhypherior's secondary ability, Solid Rock allows it to take some weaker super effective attacks, unlike Rhydon. Their movepools aren't too different either.
However if you have Eviolite, then Rhydon > Rhypherior on walling terms.