Golf Sidekick: Difference Between Breaking 70 and Breaking 80

What can cause the same golfer to shoot 80 and 69 during two separate rounds on the same golf course?

Matt from Golf Sidekick played Bangkok Golf Club and had a rather tricky time during his first round. The second round he played saw the 'Playa-in-Chief' break 70 with a 69. This is the first time he's gone sub-70 in a very long time, so what was the difference between breaking 80 and breaking 70?