The thing is the strength goal for normal service .. with a Higher Tensile Strength Steel Alloy ,
you need less of it to achieve the needed strength,

with a Lower cost steel alloy You add a Bit More for Safety Margin ,

either achieves the goal of making a functional, in this case, Bike frame.



The Steel Industry uses a Number system to indicate which minerals are combined to get the desired properties of a steel alloy

Thus the 1010 is one mix, and 4130 another ..

https://en.wikipedia.org/wiki/Alloy_steel