The AMD RX 6400 is the objective winner of this comparison, securing victory in seven out of twelve measured specifications. Its most significant advantage over the AMD Radeon RX 550 is its FP32 performance, which is 194% higher. While the AMD Radeon RX 550 maintains a 100% advantage in memory bus width, the AMD RX 6400 dominates the majority of the technical categories evaluated, establishing itself as the superior component based on the provided data.

Users prioritizing raw computational power should select the AMD RX 6400 to leverage its substantial lead in FP32 performance. Conversely, the AMD Radeon RX 550 remains the appropriate choice for specific use cases that rely heavily on a wider memory bus. Buyers should weigh the importance of these two distinct technical advantages against their specific requirements to determine which of these two graphics cards best suits their system configuration.