It's really confusing (and unnecessary) to keep switching between two kinds of percentages: compression ratio and size reduction. At least one of the illustrati

It's really confusing (and unnecessary) to keep switching between two kinds of percentages: compression ratio and size reduction. At least one of the illustrations seems to be labelled size reduction, but is showing compression ratios. Maybe they mean 'reduced size %' == 'compression ratio' when they say size reduction, in which case why use both terms?