As requirements for higher capacities came in, SD cards have grown in capacity too (SDHC is SD High Capacity, while SDXC is SD Xtended Capacity). SDHC cards typically come in capacities between 4GB to 32GB. Backwards compatibility is built in, so if a camera has SDHC support , it will support standard SD cards too.
Correspondingly, what does SDHC stand for?
Secure Digital High Capacity
Can I use SDXC instead of SDHC?
Because SDXC uses a different file system called exFAT and it works differently than standard SD cards, this new format is NOT backwards compatible with host devices that only take SD (128MB to 2GB) or host devices that only take SDHC (4GB to 32GB).
Do all cameras use the same SD card?
Both cards use the same form factor (24 by 32mm); however SDHC cards feature larger capacities and higher data-transfer speed (SDHC cards range from 4GB to 32GB, where older SD cards top out at 2GB). Nearly all SD-compatible cameras sold today accept both SD and SDHC cards, so either will work.