Comparing the two estimates:
The star count estimate is documented in Astrobiology Magazine (Hat-tip Oliver_C):
At this week's General Assembly of the International Astronomical Union in Sydney, the researchers put forward their big number: 70 sextillion, or 70,000,000,000,000,000,000,000 [seven followed by twenty-two zeros]. Previous estimates were approximately twenty-five percent smaller. "This is not the total number of stars in the universe, but it's the number within the range of our telescopes," said Driver.
There's no error range cited here, but given the previous estimates are only 25% different, using 7×1022 seems reasonable.
The grains-of-sand estimate is already discussed in another Skeptics.SE question, where Thomas_O explains:
Estimating the number of grains of sand on Earth is difficult. This source suggests 7.5x10^18 grains, but only includes beaches (deserts, under-sea sand and other sources not included.) This source suggests 10^20 to 10^24 grains.
So, the lower number there, 7.5×1018 doesn't include the deserts explicitly included in the original quote; we can discard that.
The second estimate has a wide (two orders of magnitude) error range, which covers the star estimate.
So, the estimates we have previously found of the number of grains of sand in the world aren't accurate enough to answer the question.
