The Western Digital WD Black SN8100 4TB is the objective winner of this comparison, securing victories in six out of seven evaluated specifications. Its most significant advantage over the Silicon Power UD90 1TB is its storage capacity, which is 300% larger. While the Silicon Power UD90 1TB holds a 92% advantage in MSRP, the Western Digital WD Black SN8100 4TB dominates the technical metrics, establishing itself as the superior option for users prioritizing high-volume data storage.

Users who require maximum space for large libraries or extensive file collections should choose the Western Digital WD Black SN8100 4TB for its vastly superior capacity. Conversely, the Silicon Power UD90 1TB is the appropriate selection for budget-conscious buyers who prioritize a lower MSRP over the expanded storage capabilities offered by its competitor. Each drive serves a distinct purpose based on whether the user values total capacity or initial cost efficiency.