One is 37cal per roll and shows as red on the traffic light system. The other is 40cal and shows as green. One is 6.7g salt and is red; the other is 6.7g salt and amber. Is it me or does this not make sense as a quick-glance guide to healthy eating?
All I can imagine, Jason, is that the second type of bacon-wrapped sausage weighs much more than the first (per sausage, that is, not per pack). Although the heavier sausage has a similar calorie count and salt content to the lighter one, it has fewer calories and less salt per 100g (or any other fixed weight) and is therefore 'healthier'.
To me, the real question is: why does Sainsbury's go to the trouble of offering two types of own-brand bacon-wrapped sausage?

These are actually pigs in blankets from a recipe on the Waitrose website. I don't know how they fare on the traffic light system, but they certainly look tasty...