In actual use, probably none. Concise rules would frown on the pronoun splitting the negative verb pair "did not". In American English, the contraction is more common, "Didn't I say you would find nothing there?" It seems to carry the same import to say "Did I not say you would find nothing there?" (inviting a confirmation)
difference between as on and as at
What is the difference between Florida and California What is the difference between Florida and California
what's the difference between physician and doctorwhat's the difference between physician and doctor what's the difference between physician and doctor
Difference between paging and what?
difference between enterprise and corporation
difference between enterprise and corporation
The difference between a shogun and a samurai is like the difference between a king and a knight.
just difference
Difference between it and what?
what is the main difference between polyethylene and polyesters what is the main difference between polyethylene and polyesters
The difference between Disneyland and Disneyworld is that Disneyland is in California and Florida is in Disneyworld. This is the difference between Disneyland and Disneyworld.
The difference between 9538 and 6743 is 2795.