Within vs In

[Belly T]

Does it make any difference:
In 3 days of purchase
Within 3 days of purchase
?

[Anglika]

"in 3 days of purchase" makes no sense.

"within 3 days of purchase" - up to three full days after purchasing the item

[Belly T]

So what the differences between them? within and in?
They all express the period of time, don't they?

[Belly T]

anybody?
Is it mean the same when we use:
We'll reach there within an hour?
We'll reach there in an hour?

[Anglika]

They may seem close, but there is a difference in contextual meaning.

In - preposition - expressing a period of time during which an event takes place or a situation remains the case [in an hour]

We'll be there in an hour.
The bus will arrive in two hours from now.


Within - preposition - occurring inside (a particular period of time). [within the hour]

We'll reach there within thehour.
You must send off your registration within three days of purchase.

[Belly T]

Originally Posted by Anglika

They may seem close, but there is a difference in contextual meaning.

In - preposition - expressing a period of time during which an event takes place or a situation remains the case [in an hour]

We'll be there in an hour.
The bus will arrive in two hours from now.


Within - preposition - occurring inside (a particular period of time). [within the hour]

We'll reach there within thehour.
You must send off your registration within three days of purchase.

about your In preposition, expressing a period of time during which an event takes places....
ex: we'll be there in an hour
So there event takes place here is "be", right?

and how about within
Within the hour? Wondering why I've never heard about this expression. But the event takes place here is reach? So it's similar to In?
Still can see no difference between them.