Qualitative difference claims reduce to differences of degree on a continuum.

Evidence

The way to formulate this claim of “difference in kind, not degree” is to ask “How different is object A from object B vis-à-vis concept Z?,” where A and B are members of the scope of application of the concept. It might be the case that A scores 1.0 (maximum) on the concept while B scores 0.0 (minimum): they are very different from each other. Another object C might be close to A scoring 0.9, while object D is close to B with value 0.1. As such, “qualitatively different” actually means “very different.” For example, poor people are not qualitatively different from wealthy, nor are autocratic regimes qualitatively different from democratic ones: they are “very different.” — Gary Goertz, Social Science Concepts and Measurement, 400

Categorization

• DEEPTHINKING: This dissolves a hugely common cliché of ordinary argument — ‘they’re qualitatively different’ — into a mere claim about distance along one dimension, with consequences for democracy, poverty, and mental illness alike.
• XREF: Connects to the continuum/degreeism debate in concept measurement, and to the World Bank poverty-line passage in this same chapter. — connects to: Judgements of similarity depend on the available comparative frame, not just absolute difference. — Anna X. Huang, Jacqueline M. Chen, and Juliane Degner, Being One or the Other, Both or…, 50