Answer
AB is about .66 cm closer.
Work Step by Step
Let the distance from chord AB to point O be x. Let the distance from chord CD to point O be y.
x$^2$=10$^2$-6$^2$
x$^2$=64
x=8
y$^2$=10$^2$-5$^2$
y$^2$=75
y=5$\sqrt 3$
y-x=5$\sqrt 3$-8$\approx$.66
