Unfortunately you can't really rely on this sort of comparison between numbers obtained from different sources, except in the most unambiguous circumstances, which rarely arise for a complex topic such as sector emissions and cost of mitigation. The 1.5% and 2.4% figures may use different methodologies. The total-cost-to-decarbonize estimate probably entails a variety of unrealistic assumptions; it's hard to take into account future improvements in technology, all of the different ways the market will find to minimize costs, etc.

If you're interested, I discuss the general danger of working with such quick-grab numbers in https://climateer.substack.com/p/numbers.