They apply to universal concepts (classes) and not individuals.
Is the ‘note’ of essence that is common to all of its subspecies. Example: A Bus is a Truck
- Specific Difference
This distinguishes a species from all other species in its genus.
What individuals (instances – both form and quantity) have in common with their class (form only).
Property flows necessarily from essence. Wherever that class extends, so does this property. It is, however, not a specific difference or part of the essential definition of that class.
Exists only contingently. They may or may not accompany the essential presence of the predicated subject.