This paper presents a systematic reanalysis of experimental data on condensed matter nuclear reactionsaccumulated over the past three decades. Based on the physical fact that deuteron wavefunctions are confinedwithin nanoscale potential wells in condensed matter environments, we argue that traditional approachesemploying free-space conceptual frameworks—such as “equivalent temperature,” “kinetic energyenhancement,” and “electron screening”—to interpret the data constitute a subtle category mistake. Throughstatistical comparison of effective fusion rate constants between carbon-based systems (n=31) and metal-basedsystems (n=18), we identify a robust eight-fold difference (p<0.001), which can be independently explained bythe geometric effect of confinement scale. This indicates that the baseline fusion probability is determined bythe material’s microscopic geometry. Segmented power-law analysis further reveals that the system exhibitssuperlinear power growth (α=1.28) when the volume is below the critical volume, and tends toward linearity(α=0.89) beyond it—a behavior consistent with the spatial boundary conditions of network coherence. Basedon this analysis, we propose a fundamental taxonomic distinction between cold nuclear fusion and hot nuclearfusion: hot fusion relies on kinetic energy to overcome the Coulomb barrier and is a deterministic process; coldfusion relies on spatial coincidence upon wavefunction collapse and is a non-deterministic, stochastic process.This taxonomy redefines the theoretical foundation and engineering direction of condensed matter nuclearreactions.