Memory cards & SD cards contain only one memory IC, which is a press IC printed on a PCB. SD Memory Card & USB Memory Card use only 4 communication channels: + 5V, Ground, SCL Data out, SDA Data out. Therefore, SD Memory Card Readers use an SD card slot with a variety of jacks and only use a USB jack.
The microprocessor IC receives the SCL and SDA data paths sent from the USB, SD memory card and communicates between the memory IC & the microprocessor IC, extracting the data from the USB and SD memory cards and using the compressed data as input data.