The Samsung 990 Pro 4TB is the objective winner of this comparison, securing victories in five out of seven measured specifications. Its most significant advantage is its storage capacity, which is 300% greater than that of the alternative. By offering substantially more room for data, the Samsung 990 Pro 4TB provides a clear technical lead for users requiring high-volume storage solutions compared to the Silicon Power UD90 1TB.

Choose the Samsung 990 Pro 4TB if your primary requirement is maximum storage capacity for large files or extensive libraries. Conversely, the Silicon Power UD90 1TB is the better option for budget-conscious buyers, as it holds an 87% advantage in MSRP. Selecting between these two drives depends entirely on whether your priority is the expansive space offered by the former or the lower cost provided by the latter.