Buy: considered as a general term, which is most commonly used to refer to everyday goods and small products. Example: I bought a new phone. Purchase: considered to be a more formal word than buy, and is often used to refer to contracts and big products.

When used as nouns, buy means something which is bought, whereas purchase means the act or process of seeking and obtaining something (e.g. property, etc.). When used as verbs, buy means to obtain (something) in exchange for money or goods, whereas purchase means to pursue and obtain.

Purchase and Buy are two terms that essentially mean the same thing: acquiring something in exchange for money. However, the word "buy" is generally more casual and is commonly used in everyday speech. You're more likely to hear someone say they're going to "buy groceries" rather than "purchase groceries."

Both ' buy ' and ' purchase ' refer to the act of acquiring something in exchange for money or other forms of payment and are sometimes used interchangeably. However, 'buy' is more general and commonly used while 'purchase' is typically used for larger and more expensive items and is a more formal term.