Could be that they've replaced the Sodium Chloride with Potassium Chloride? Reduces the Sodium content of the crisps so they advertise as "45% less salt" as people are trying to reduce salt intake and it easier to understand at a glance than "45% less Sodium". Still probably has the same amount of "salt" in there but it's a Potassium salt rather than a Sodium salt.
The "45% less Sodium" I mentioned above would likely be incorrect as they can mess with the percentages reported by using either atomic weight of sodium (~23 g/mol) or molecular weight of Sodium Chloride (~58.5 g/mol) depending on which one gives a better percentage for their marketing blurb.