SDHC vs SDXC
SD (Secure Digital) has now become the most popular standard for memory cards as it is used by a majority of mobile phones, tablets, and other devices. From the SD standard arose the newer SDHC and SDXC standards. Although the two are still commonly referred to as SD cards, there are a number of differences between SDHC and SDXC cards; the most major of which is capacity. SDHC was created when the 2GB limit of the original standard was reached, and it had a much larger limit of 32GB. But a short time thereafter, it became apparent that the 32GB limit would be surpassed in just a matter of a few years. Thus the SDXC standard was created even before 32GB SDHC cards appeared on the market. The theoretical limit of SDXC cards reach 2TB, but the currently available SDXC cards on the market today only have a 32GB capacity.
Aside from the increased capacity, another difference between SDHC and SDXC is speed. The fastest SDHC memory cards can reach a maximum speed of 12.5MBps. Of course there is always the minimum speed, which is designated by what class it belongs to. In comparison, SDXC cards can reach speeds of up to 104MBps. It is significantly more than that of SDHC and is suited for devices that need this high rate like high-resolution digital cameras and HD video cameras.
Although SDHC and SDXC are electrically compatible, they do not use the same formatting, which will result in older hosts to not recognize SDXC memory cards. SDHC uses the very popular FAT32 format while SDXC uses the more recent exFAT format. SDHC has the upper hand at this moment as most of the devices that use memory cards can read FAT32 but not exFAT. This is probably going to change in the future as manufacturers include compatibility with the newer standard.
Lastly, there is the issue of size. SDHC memory cards come in three sizes; the standard size used in most DSLRs, the mini, and the micro for most mobile phones. Currently, SDXC memory cards are only available in the standard size. The smaller sizes will probably appear in the future when the demand for them appears.
Summary:
1.SDHC has a limit of 32GB while SDXC will have a limit of 2TB.
2.SDXC is much faster compared to SDHC.
3.SDHC uses FAT32 as its default format while SDXC uses exFAT as its default.
4.SDHC is available in three sizes while SDXC is currently available in one.