Both are probably exaggerated by an inch or two but they're still pretty tall by average population standards. Nash looks like a squirt on TV but he would tower over most getbiggers.
Most men exaggerate their height. Very few people actually measure their height accurately so just rely on educated guesses to how tall they are - usually being generous to themselves by an inch or two.
A man who's a legit +6'3ft stands out in a crowd of people.