cstr

According to http://dictionary.law.com/, "declaration" means:

"1) any statement made, particularly in writing.

2) a written statement made "under penalty of perjury" and signed by the declarant, which is the modern substitute for the more cumbersome affidavit, which requires swearing to its truth before a notary public."

Therefore, you may say "statement" is what you state in oral or written forms and "declaration" is referred to a written statement.

But does it make difference?