Your question is mostly correct, but a bit of refinement would make it more natural. Here’s a corrected version:
"Is there any difference between saying 'I agree' and 'Agreed'?"
Now, to answer your question:
Yes, there is a slight difference between "I agree" and "Agreed."
1. "I agree" – This is a full sentence and is more standard in formal and informal conversations. It clearly states that you personally agree with something.
* Example: "I agree with your point about sustainability."
2. "Agreed" – This is more of a shorthand or a conversational way to express agreement. It’s often used in informal settings or written discussions.
* Example: "This is the best way forward." → "Agreed."
Both convey the same idea, but "Agreed" is more concise and sounds slightly more assertive or final.