Thyroid nodules are among the most frequently encountered endocrine abnormalities, with an increasing incidence due to widespread use of ultrasonography. Although the majority of thyroid nodules are benign, accurate identification of malignant lesions is essential for appropriate management. Fine-Needle Aspiration Cytology (FNAC) has long been considered the first-line diagnostic procedure because of its simplicity, safety, and cost-effectiveness. However, nondiagnostic and indeterminate cytological findings remain important limitations. Core Needle Biopsy (CNB) has emerged as a complementary diagnostic technique capable of providing preserved tissue architecture and reducing inconclusive diagnoses in selected patients. This review compares FNAC and CNB regarding diagnostic accuracy, indications, limitations, complications, procedural characteristics, and current clinical recommendations. Published evidence demonstrates that FNAC remains the preferred initial diagnostic modality for most thyroid nodules, whereas CNB provides additional diagnostic value in repeatedly nondiagnostic aspirates, indeterminate lesions, and selected suspicious nodules. Optimal patient outcomes are achieved by integrating imaging findings, clinical assessment, and appropriate pathological evaluation. Future advances including molecular diagnostics, artificial intelligence, and standardized reporting systems are expected to further improve diagnostic precision while minimizing unnecessary surgery.