SDHC, or Secure Digital High Capacity cards are high-capacity memory cards, which evolved from standard SD cards. Both types of cards work with digital devices such as cameras and cell phones,and devices that accept SDHC cards will also accept SD cards.
SDHC cards start to write data at a specified speed from 2MB/sec to 6MB/sec, and sustain that speed, while SD cards start at 0MB and build speed. As the need for larger capacity storage and the speed of devices has increased, most digital devices now use SDHC cards. SDHC card capacities typically range from 6 to 32GB, while SD cards are limited to 2GB of storage.