Answer
$\frac{2}{3}$ is larger by $0.000666\bar6$
Work Step by Step
We see that $\frac{2}{3}$ is larger (it has more repeating 6's):
$\displaystyle \frac{2}{3}=0.6666\bar6 \gt 0.666$
$\displaystyle \frac{2}{3}$ is larger by:
$0.6666\bar6-0.666=0.000666\bar6$
