An association is a connection between things and ideas. For example when we think of a boot we may think of our feet, the heel of our feet, or the sole of our feet.
Example: Association for the word: bicycle [pedals, hangar, bowl, pump, gangway]
Classification is related to categorization. When we classify, we are arranging people, objects, or ideas into groups of its kind or class according to its shared characteristics.
All things can be divided into two classes: animate (living things) and inanimate (things having no life). Objects can be placed in a certain general classes because of their resemblance, purpose, or use.