buy and purchase

[tp123456]

Hi,
I would like to know the difference between 'buy and purchase'. IS there any rule to use these words?
As far as I know purchase is used for non-living things only where buy can be used with living thing e.g persons.
Make correction if I am wrong.

[Uncle M]

Their meanings are exactly the same and neither is restricted in terms of what is bought (past tense of buy).

Purchase is a slightly more formal verb, but can also be used as a noun:

a purchase = something that is bought

The noun purchase has another meaning: for example, rubber soles give better purchase on slippery surfaces - purchase here means grip.

Hope this helps.

Dave