A few differences exist between SD and SDHC memory cards. Both cards are used for storage on many devices, including digital cameras, MP3 players and netbooks. The SD and SDHC memory cards are the most popular format for storing data like pictures, music and general documents.
The acronym SD stands for Secure Digital while SDHC stands for Secure Digital High Capacity. Many companies, such as Kodak, Sandisk and PNY, make SD and SDHC cards. The manufacturers formed the SD Card Association and oversee and create standards for the format.
SD Cards have a storage capacity of 512MB to 4GB. SDHC cards have higher storage capacities, running from 4GB to 32GB.
Because of the larger storage capacities, the SDHC card writes at speeds from 2MB to 6MB per second, as mandated by manufacturers. The SD card writes and speeds less than 2MB per second.
SDHC cards are excellent for digital cameras that take high quality photos because they tend take up more storage and can write the large file quicker. SD cards, because of the slower write speeds are used better in lower-end cameras and MP3 players.
SD cards used a Fat 12/16 storage system. For the SDHC cards, this was changed to a Fat 32 system because of the large storage capacities.