Understanding the subtle difference between these two auxiliary verbs and putting them to use at the right place will make us better speakers.
In English there is a significant difference between the uses of would and will. Knowing when to use the terms correctly is an important part of mastering the English language.
Will and would are both types of auxiliary verbs that are known as modal verbs. Other modal verbs include: could, shall, might, may, can, ought to and must. Modal verbs don’t really have any meaning on their own, but act as helpers to give further meaning to other verbs.
Will is a definite statement, which means that you use it when you are certain that the future action is going to take place. For example: “I will go and collect the mail in the morning”. When you use will you or the subject executing the future action is committed to it being carried out.
The modal verb will can be used to talk about quick decisions, promises, offers and a likely prediction. For example: “I think I will take the bus instead of walking.” instant decision; “I’ll get the dog washed tomorrow.” promise; “I will help you with your homework after dinner.” offers and “I’ll bet she spent a lot of money on that dress.” likely predictions.
Will is also used as a first conditional, which is used for cause and effect in situations that are not changeable. For example: “If it rains, you will get wet,” or “If you are late to work, you will get in trouble.”
Would is an English modal verb and has many different uses, which include: invitations, requests, asking permission, talking about preferences and making arrangements. For example: “Would you like to come to the party on Saturday?” is an invitation; “Would you be able to post this parcel for me?” is a request; “Would I be able to leave early today?” is asking permission; “Would you like steak or chicken for dinner?” or “I would prefer to eat ice cream” are both examples of talking about preferences and “Would Friday at 8pm suit you?” or “Saturday at 6pm would suit me.” are ways to make arrangements using would.
Would is also used in second and third conditional statements, which are used to talk about imaginary or unlikely situations. For example: “If I knew where he lived, I would visit him,” Is a second conditional statement. An example of a third conditional statement is thus: “If I had known about the party earlier, I would have gone.” This is used to express an imaginary situation that took place in the past.
Summary:
1.Would and will are both auxiliary modal verbs.
2.Will is used to talk about definite future actions.
3.Will is used to talk about: quick decisions, promises, offers and a likely prediction
4.Would is used to talk about: invitations, requests, asking permission, talking about preferences and making arrangements.
Both will and would can be used in conditional statements.
Source: http://www.differencebetween.net/language/difference-between-would-and-will/
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