"Thanks" or "thank you"?

Solution 1:

They're both correct. "Thanks" is slightly more informal, but otherwise, they both mean the same, a statement of gratitude.

Although they're both correct, they have a difference.

"Thanks" is a noun, and can be used like this:

Give James my thanks./ I give you my thanks.(when speaking face to face)

Hence, the today's expression, "Thanks, Jim".

"Thank you", the "thank" is a verb, and is actually a shortening of the phrase "I thank you". So, you'd probably not say "Give Jim my thank-you", but "Give Jim my thanks."

Otherwise, they are interchangeable.

Solution 2:

Thanks is another way of saying thank you.

The difference is that thanks is a noun used for

• An expression of gratitude: "Festivals were held to give thanks for the harvest."
• A feeling of appreciation: "They expressed their thanks and wished her well."

Thank is a verb, and it means "express gratitude."