Concrete Nouns vs. Abstract Nouns

What is the difference between Concrete Nouns and Abstract Nouns?

Concrete Nouns are nouns that can be touched or seen. They have some physical properties. Unlike Concrete Nouns, Abstract Nouns do not have physical properties and are only perceptions. They are intangible ideas, feelings, attributes, or characteristics.

examples:

For Abstract Nouns, acts of their kind, such as sweetness or gentleness may be seen, but not sweetness and gentleness since they are just perceptions or concepts. The same explanation applies to the remaining examples in the Abstract Nouns column.