Epilepsy is a common neurological disorder experienced all over the world. The electroencephalography (EEG) signal that originates from the brain’s electrical activity is pivotal for identifying and tracking seizures. This chapter provides a reliable approach to distinguish the seizure brain states, particularly in focal and generalized seizure patients, based on the subsequent analysis of the EEG signals using Fast Fourier Transformation (FFT) and Welch Power Spectral Density (PSD) approaches to determine the spectral features considering the amplitude belonging to the delta, theta, alpha, beta, and gamma wavebands. The systematic examination of the seizure patient’s data leads to the determination of the sub-bands and spectral thresholds, which in turn allows the identification of the most significant EEG wave bands and respective brain states to reveal the differentiation between focal and generalized seizures. This chapter represents a significant step toward an understanding of seizure wavebands for improved diagnosis and treatment approaches.