Final answer:
The two main families of flash memory cards are the non-volatile types such as SD, MS, xD, and CF cards. They differ in memory capacity ranging from MBs to GBs, and speed rated by MBPS or class rating, with Class 10 being faster than Class 2.
Step-by-step explanation:
The two different families of flash memory cards used in digital cameras are primarily Non-Volatile memory cards, such as SD (Secure Digital), MS (Memory Stick), xD (Extended Digital), and CF (Compact Flash). These cards vary in capacities, from MB (megabytes) to GB (gigabytes), where a higher capacity means the card can store more images.
In addition to capacity, flash memory cards are also rated by speed to ensure efficient data transfer. Speed ratings can appear in different formats, including megabytes per second (MBPS), an 'x' suffix that follows a speed number, and a class rating. However, the class rating is the most commonly used and easiest to understand, with Class 10 cards providing a minimum transfer rate of 10 MBPS and Class 2 cards at 2 MBPS. When shooting high-quality photos or high-definition video, a higher class card is recommended for its faster speed capabilities.