What does "greater" mean? I buy into the idea that the attack that breaks SHA-2 is unlikely to break SHA-3, and vice versa, and that's apparently a key design goal for the standard.
"greater" here means that we would think that SHA-2 is easier to break than SHA-3. Technically speaking, it's a guess, but I think that the general consensus is that it is more likely that SHA-2 will be broken before SHA-3.
