Key Difference: 'Hi' and 'hello' are two frequently used forms of greeting. They both are synonymous. However, Hello is regarded to be more formal than Hi.

Conversation is an important ingredient of a person’s social life. People like to interact with each other to express their views, opinions and thoughts. It can either be a formal conversation or just an informal conversation. The initial point is to address someone before starting the actual flow of words. This is done by using one of various greeting words like hello, hi, hey, etc.

The two most common greeting words are hi and hello. They can be used to address any person irrespective of gender or age. There is just a small difference between the two and that too depends upon the individual’s choice. 'Hi' is simply regarded as an informal version of ‘Hello’. It is generally used to address the friends or people of the same age as the addressor. On the other hand, hello has achieved the status of the standard adressing term while initiating a conversation on phones.

Oxford Dictionary defines hello as an exclamation which is “used as a greeting or to begin a telephone conversation”

According to the Oxford Dictionary the word 'Hello' originated in the late 19th century as a variant of earlier hollo which is related to holla.

It may also be used in the plural form (hellos). For example: She was greeted with several hellos from her friends. Hello may also be used in different situations in different forms. In England, it is also used to express astonishment. It may also be used as a cry in order to get noticed by the other people. Sometimes, hello is also used as an expression denoting an expression of sarcasm or anger.

Comparison between Hi and Hello:

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