There is a medical distinction between “Guts” and “Balls”.
We've heard colleagues referring to people with “Guts”, or with “Balls”.
Do they, however, know the difference between them?
Here’s the official distinction; straight from the British Medical Journal: Volume 323; page 295.

GUTS - Is arriving home late, after a night out with the lads, being met by your wife with a broom,
and having the “Guts” to ask: “Are you still cleaning, or are you flying somewhere?”

BALLS - Is coming home late after a night out with the lads, smelling of perfume and beer,
lipstick on your collar, slapping your wife on the bum and having the “Balls” to say: 'You're next, Chubby.'

I trust this clears up any confusion.

Medically speaking, there is no difference in outcome; both are fatal.