I'm not an expert or no expert

[Avehayyan]

Greetings everybody,

I'm not an expert in the subject but we might share some reflections on the thought (of organizing a conference on the subject).

Which one is better? (I'm not an expert) or (I'm no expert)? What's the difference between them?

Thank you in advance.

[5jj]

There is no real difference.
There isn't a real difference.

Possibly 'no' is slightly more formal than 'not a(n)'