Question is if mass and force are different things why can tons(mass) be converted to ton-force just by changing the units to “ton- force”? Same with lbm and lbf.
It’s because it works if one uses standard gravity.
Newtons 2nd law: F = ma.
ɡ₀ = standard gravity
a = ɡ₀
F = mɡ₀
The actual conversion is confusing and requires getting the units correct but there’s an explanation here.