The main purpose of this article was to explore the differences between common factor analysis (CFA) and principal component analysis (PCA) through literature reviews. Seven topics were discussed: (1) Factor or Component? (2) Rationales of CFA; (3) Rationales of PCA; (4) Comparisons of rationales between CFA and PCA; (5) Comparisons of empiric evidence between CFA and CPA; (6) Comparisons of abstracting procedures between CFA and PCA; (7) Comparisons of applications and interpretations between CFA and PCA. At the end of this article, a final comparison table, including the sameness, the differences, and the conditions of similarity between CFA and PCA was exhibited.