Hardness
Depending on whether your hardwood floor is for commercial or domestic use, you might want to consider the hardness of the timber you choose. Generally, hardwood floors have a janka rating of 5 and above, suitable for commercial and heavy traffic.

The Janka rating system
This system is a quantified measure of the hardness of timber. It measures the force needed to drive a stell ball to a depth where half the ball is imbedded in the wood. The more resistant the timber, the higher the Janka rating

Durability

The term "durability" refers to the natural ability of the hardwood to resist attack from biological hazards such as fungal attack or in high-risk conditions such as low ventilation or high humidity.
The durability clasess are:

Class 1 - highly durable
Class 2 - durable
Class 3 - moderately durable
Class 4 -non - durable