Annuity factor

Hi,

Annuity factor in my corporate finance books is like 

AF = (1+K)^N-1/K(k+1)^N

and on websites it is showing as

AF = 1-(1+r)^-N/r

Just like R & K denote the discount rate, do both the formulae mean the same? 

I did calculations on pen and 1st formula gives 1.73.10, 2nd value gives 1.73

I checked PVAF table its 1.73, I used online PVIFA calculator its 1.73

r=10% and t=2years

Txs.