What we call "scrypt" is actually scrypt(N=1024,R=1,P=1).  Nscrypt (more correctly, adaptive-n-scrypt) means that N gets larger based on a certain schedule (e.g. at block X, n increases).  Currently, all relevant nscrypt coins are at N = 2048 = 2^11.  EXECoin and Vertcoin (in example), will increase to scrypt(N=4096,R=1,P=1) at a certain block, and N will double again (or considering N=2^n, n will increase by 1) at another specific block.

This means that 'nscrypt' (scrypt(N=2048)) takes twice as much memory as 'scrypt', and therefore the hashing speed is reduced by ~50%.

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228% vs LTC so far today, with only 2 nscrypt coins!  Variance is obviously going to play a factor with the low hashrate so far, but that's looking darn good.