One difference between them is how formal they sound. Compare the following sentences.

Put "buy" or "purchase" in the space.

<em>I would like to ______ a new home.</em>

<em>She wants to _____ a hamburger.</em>

Like most English speakers, I would say "purchase" for the home and "buy" for the hamburger. You probably wonder, why does English have two words with exactly the same meaning?

you asked how to use "buy" and "purchase." We usually use "buy" as a verb. For example,

<em>I will buy food for the party.</em>

It is not so common to see "buy" as a noun, but you do find it in cases like this:

<em>The police stopped a drug buy on the street.</em>

We often use the verb "purchase" for when legal documents are involved, such as in:

<em>The government purchased a new contract for 1,000 airplanes.</em>

And you should use "purchase" when you need a noun form, as in:

<em>You made a smart purchase when you bought gas before the price went up.</em>

<em></em>

In summary, try to use "buy" for simple actions, and "purchase" for more formal exchanges of money for goods.

There's no major difference. Purchase is a bit more formal, whereas buy is generally used in everyday language.

'To buy something' and 'to purchase something' mean the same thing when either 'buy' or 'purchase' is used as a verb. However, in other circumstances, there are some important differences.

A purchase is something that you buy.

<em>[formal]</em>

<em>She opened the tie box and looked at her purchase. It was silk, with maroon stripes.</em>

*Actually, we could use buy here too if we wanted, but next we'll see an important difference.

*We can not use the noun 'buy' as a one-for-one substitute in this sentence (if the cars were purchased at different times and further detail is not given). Rather, we would need to use the word 'buying' (the <em style="color: rgb(34, 95, 115);">present participle </em>of the<em style="color: rgb(34, 95, 115);"> verb 'to buy') </em>instead<em style="color: rgb(34, 95, 115);">.</em>

Additionally, the word 'purchase' in the example sentence can either refer to one purchase of several cars and/or several purchases of one car or multiple cars. Thus, simply using the word 'buy' as one-to-one substitute here doesn't work and doesn't approach the functionality that the word 'purchase' has in the example sentence.

VARIABLE NOUN [oft <em style="color: rgb(102, 102, 102);">a</em> NOUN]

If you <a href="https://www.collinsdictionary.com/dictionary/english/get" rel="noopener noreferrer" target="_blank" style="color: inherit;">get</a> a purchase on something, you <a href="https://www.collinsdictionary.com/dictionary/english/manage" rel="noopener noreferrer" target="_blank" style="color: inherit;">manage</a> to get a firm <a href="https://www.collinsdictionary.com/dictionary/english/grip" rel="noopener noreferrer" target="_blank" style="color: inherit;">grip</a> on it.

<em>[formal]</em>

<em>I got a purchase on the rope and pulled. </em>

<em>I couldn't get any purchase with the screwdriver on the damn screws.</em>

Example:

<a href="https://books.google.com/books?id=WUaWAwAAQBAJ&pg=PA120&dq=%22purchase+on+the%22&hl=en&newbks=1&newbks_redir=1&sa=X&ved=2ahUKEwi28uKz6v3qAhWRj3IEHduzAIk4jAEQ6AEwAnoECAMQAg" rel="noopener noreferrer" target="_blank" style="background-color: rgb(255, 255, 255); color: rgb(102, 0, 153);">On Being Here to Stay: Treaties and Aboriginal Rights in Canada</a>

Michael Asch

(Page 120)

<em style="color: rgb(60, 64, 67);"></em>

This kind of usage tends to be archaic to an extent and is seems to be mainly found in older texts from past centuries or newer primarily literary texts like poems and novels.

There is no difference in meaning.

"Purchase" is more formal. In everyday life, for ordinary things, we use the word "buy." However, in a company, the departing in charge of buying things is called the "purchasing" department because it sounds more dignified.

This follows a very common pattern in English. Due to history, English has two sources for its core vocabulary, Anglo-Saxon and Latin. "Buy" is from Anglo-Saxon, "purchase" is from Latin. Anglo-Saxon words are the words used most often in everyday spoken English. Latin-derived words are more formal, and to be used in dignified and in written English.