What is the difference between AISI 4140 steel and 27SiMn material

What is the difference between AISI 4140 steel and 27SiMn material?
AISI 4140 steel is alloy structural steel, with high strength and toughness, good hardenability, no obvious temper brittleness, high fatigue limit and multiple impact resistance after quenching and tempering treatment, and good low-temperature impact toughness. AISI 4140 steel is suitable for manufacturing large and medium-sized plastic moulds with certain strength and toughness.

Chemical composition of AISI 4140 steel: C: 0.33-0.48, Si: 0.15-0.35, Mn: 0.75-1.00, S: ≤ 0.030, P: ≤ 0.030, Cr: 0.80-1.10, Mo: 0.15-0.25.

27SiMn material belongs to alloy structural steel. 27SiMn material is mainly used in quenching and tempering state to manufacture hot stamping parts with high toughness and wear resistance; it can also be used in normalizing or hot rolling supply state, such as tractor track pin, etc.

Chemical composition of 27SiMn material: C: 0.24-0.32, Si: 1.10-1.40, Mn: 1.10-1.40.