The primary difference is that the standard is an NVMe-only bridge. The RTL9210B adds the SATA bridge functionality, making it more versatile for users who may swap between different types of M.2 drives. Performance & Reliability RTL9210B-CG - Realtek
: Supports 32Mbytes external SPI Flash for firmware, customized LEDs (blinking frequency/duty cycle), and GPIO/UART/I2C interfaces for advanced system integration. Performance and Compatibility
The is a dual-protocol USB bridge controller that enables high-speed data transfer between a USB host and either NVMe (PCI Express) or SATA storage devices. Key Technical Specifications (2021 Datasheet)