Intent and intention share meanings and overlap in use, but they are not completely interchangeable.
Both words mean "the thing that you plan to do or achieve : an aim or purpose."
Often they can be used interchangeably:
She thinks I'm trying to make things difficult for her, but that's not my intent/intention.
It was the explicit intent/intention of the architect to suggest a church steeple.
The president signaled his intent/intention to meet with his allies.
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Intention implies little more than what one has in mind to do or make happen:
He announced his intention to marry.
It was not my intention to hurt your feelings.
I had every intention to pay my bills yesterday.
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However, intent suggests clear reasoning or great deliberateness and is used in more formal, legal, or official-sounding language:
the clear intent of the court's ruling
Moscow's intent is to exploit the riches and technology of the West.
The prosecutor needs to demonstrate criminal intent.