Difference between How and Why

Key difference: ‘How’ and ‘Why’ are two questions, which can be used for various purposes in the English language. The main difference between the two is that, how is used to know the manner in which something has happened, whereas why is asked to find out the reason behind it.

A question is generally asked to know about something, to understand something, to seek something, to get an answer, etc. ‘How’ and ‘Why’ are two such questions, which can be used for various purposes in the English language. However, they differ in the manner that they are used and what type of answers they are seeking.

The main difference between the two is that, how is used to know the manner in which something has happened, whereas why is asked to find out the reason behind it. For example: ‘How did you get here?’ I took the bus. ‘Why did you come here?’ Because I wanted to see you.

Dictionary.com defines ‘how’ as:

In what way or manner; by what means?: How did the accident happen?
To what extent, degree, etc.?: How damaged is the car?
In what state or condition?: How are you?
For what reason; why?: How can you talk such nonsense?
To what effect; with what meaning?: How is one to interpret his action?
What?: How do you mean? If they don't have vanilla, how about chocolate?
(Used as an intensifier): How seldom I go there!
By what title or name?: How does one address the president?
At what price: How are the new cars going, cheaper than last year's models?
By what amount or in what measure or quantity?: How do you sell these tomatoes?
In what form or shape?: How does the demon appear in the first act of the opera? How does the medication come?
The manner or way in which: He couldn't figure out how to solve the problem.
About the manner, condition, or way in which: I don't care how you leave your desk when you go. Be careful how you act.
In whatever manner or way; however: You can travel how you please.
Informal. That: He told us how he was honest and could be trusted.

As seen from the long list, ‘how’ is a word that has many different meanings. It can be used in various manners and asked to get a variety of information. It is generally used to ask the manner in which something has happened, to the extent something has happened or the condition of something.

Examples:

How do you make this recipe?
How could such a terrible accident take place?
How tall is he?
How much for a kilo of grapes?
How is Bill now?
We asked how we could help.
Let me tell you how we'll pay for the trip.
The book tells the story of how the company was founded.
She explained how she came to live here.
I don't know how the service is at the new restaurant.
I remember how they fought.
Be careful how you talk; you could get fired.
She told us how she had to work hard.
He knows how you are a valued employee.
It's amazing how they completed the bridge so quickly.
Better understand the need for clean energy and learn how to be part of the solution.
How to grow and arrange a hydrangea wedding bouquet.
See how to get the look of built-in floating shelves, with less cost and more flexibility.

‘Why,’ on the other hand, is used to inquire about something, or to ask for an explanation about a situation. It is mainly used to seek the reason, cause, or purpose for something. It is more of an authoritative question. It demands an answer, as to ‘why did this happen?’ or ‘why did you or didn’t you do this.’ For example: Why is she at the party? (I want to know the reason.)

As ‘why’ is a standard form of a question, it is used in a standard question form, which means that the subject and verb are inverted. In a question format, the subject follows the verb, such as ‘Why did you say that?’ as opposed to a regular sentence format which is subject verb object, e.g. ‘You did say that.’ This is also the case for how but only when it is being used as a question. In a sentence, the format would still the traditional ‘subject – verb – object’.

Dictionary.com defines ‘why’ as:

For what? For what reason, cause, or purpose?: Why did you behave so badly?
For what cause or reason: I don't know why he is leaving.
For which; on account of which (usually after reason to introduce a relative clause): the reason why he refused to go.
The reason for which: That is why he returned.
A question concerning the cause or reason for which something is done, achieved, etc.: a child's unending hows and whys.
The cause or reason: the whys and wherefores of a troublesome situation.
(Used as an expression of surprise, hesitation, etc., or sometimes a mere expletive): Why, it's all gone!

Examples: