I am confused about the difference between a concrete noun and an abstract noun?

A concrete noun refers to something that we can see, touch, smell, taste or quantify. In this sense concrete nouns are normally objects, or the name of something or someone. An example of a concrete noun is a table, chair or a place name, such as London.
An abstract noun refers to a concept, idea, or feeling. You cannot touch or see an abstract noun. An example of an abstract noun is love, freedom or generosity.