No Difference - by design in the Bitcoin source code.
This is the block chain's control theory feedback loop:
60minhr∗24hrday∗7dayweek 10minblock=2016 in 2weeks
Tcurrent=Tprior∗tprior/2weeks
D=work/2(32)=2(256)/(Tcurrent+1)∗2(32)
hashes/second≈D∗2(32)/600
The current target for the block chain is determined by a calculation, so any two clients looking at the block chain will calculate the same target. This calculation aims to adjust the target such that one block will be mined every 10 minutes, no matter how much total computing power is devoted to mining. The target changes every 2016 blocks based on the timestamps within those blocks. Why 2016? Because Satoshi decided two weeks was a good interval, and at 10 minutes per block, 2016 blocks will be mined every two weeks.
When 2016 blocks take more than two weeks to mine, the target goes up to make mining easier; when they take less than two weeks, the target goes down to make mining harder. In symbols, if Tprior is the previous target and tprior is the time it took to mine 2016 blocks using that target, then the updated target Tcurrent is just.
The target is typically a huge number well in excess of 2(200). Also it goes down as the total hashing power of the miners goes up. Consequently, interested people usually think in terms of the difficulty instead. Definition: The Bitcoin difficulty is the average number of nonces you have to try to find a valid block — aka. the work — divided by 2(32)(roughly 4 billion).
Note that D is just a number for human consumption. It scales in direct proportion to the computational effort required for mining, so twice the difficulty means twice the effort.
If we know the current difficulty D, we can estimate how fast all miners are hashing in aggregate. On average, it takes D∗2(32) hashes to find a nonce that works, and the target is selected to make that take 10 minutes.
I assume some of the smart answers were trying to say that it will have an impact if assuming the difficulty change happens right now today, and tomorrow you double the hash power, the 2016 blocks will be found sooner, by roughly a week before the difficulty changed to compensate for the increased hash rate, meaning that the "Revelation block" will happen 1 week sooner, assuming no other changes impacted it after this event.
