What is the difference between denotation & connotation?

Words (in any language) can have three types of meanings: primary, secondary and tertiary. 'Denotation' is the primary meaning of a word, that is, the dictionary meaning of a word or the definition of a word. The English word 'cat' denotes how the word is defined in a dictionary (all dictionaries will agree on this meaning). 'Connotation' is the secondary as well as tertiary meanings of word. The word 'cat' can be used as a metaphor to connote 'a cunning person.' As a tertiary meaning 'cat' can be used as a symbol to suggest an entirely different meaning from the primary as well as secondary meaning.  

• Denotation refers to the explicit literal meaning of a word, the "dictionary definition."¨ For example, if you look up the word snake in a dictionary, you will discover that one of its denotative meanings is "scaly, legless reptiles found in most tropical regions."
• Connotation, on the other hand, refers to the implicit associations that are connected to a certain word or the emotional suggestions related to that word. The connotations for the word snake could include evil or danger.

Ex.

There is a snake in the Kitchen (an animal, a reptile).----------> denotation

This man is a snake (dangerous).--------------------> connotation