SD vs SDHC flash memory cards?

I'm confusedd. I thought SD cards coud only reach 2GB of capacity and only SDHC (also known as SD 2.0) could do more. But I find various SD cards of 4GB.





I also seem to notice that the fastest SDHC cards (class 6 = 6MB/s) are slower than the fastest SD cards (150x = 150x150kB/s = 22.5MB/s).





Why bother with SDHC then?

SD vs SDHC flash memory cards?
The 4 GB plain SD cards don't strictly conform to the specifications of the SD Association. There may be compatibility issues, although in practice these cards are known to work with many devices. For more information, see towards the end of page 3 in the report on SD cards at the web page mentioned under "Sources" in this answer. If you want to be sure to be safe, the SDHC cards are definitely compatible with 4 GB or more, as long as your device specifies that it supports the SDHC format. (Only the newest devices support SDHC, older ones will only accept plain SD cards.)
Reply:go with just plain SD cards then