"hard/soft wood" has nothing to do with HARDNESS.
It's whether deciduous or not.
BALSA is classified as a "hard wood"
Wood is often classified into two categories including hardwood and softwood. But, the difference between these two types of wood isn’t in their name. That is, hardwood isn’t necessarily denser than softwood.
For instance, yew wood is classified as a softwood but is considerably tougher than certain hardwoods. Likewise, balsa wood is classified as a hardwood and yet it’s one of the least dense and softest types of wood.
https://www.horizonwood.com/hardwood...erence-part-1/
Why is pine a softwood?
Softwoods have no visible pores, which means that they don't display the prominent grain seen in hardwoods. ... You can identify most hardwoods due to their broad leaves, while softwoods usually have needles and cones. Examples of softwood trees include: Pine.