Quite a few will say that in picking an SD memory card for your camera doesn’t matter, or that they are all the same. This is simply not true. There are several types of memory cards.
If you’re just starting out or just do photography as a part time hobby then generally speaking, the most important feature to look for is capacity. Different file types, compression and resolution all affect the size of each file, so the number of images you can put on one card from one camera to the next is never the same. Between 1GB and 8GB storage should be enough for an average beginner photographer.
When things get a bit more serious, enthusiast and professionals need to look for a speed card. Most DSLRs produce large Raw files, shoot HD video or capture multiple shots in a single burst, the data streaming through the camera’s buffer will need to be met by a card at the end that can ‘match up’ to its specification to receive all the information.
A card’s read speed describes how fast data can be retrieved from a card. This performance is seen when transferring card contents to computers and printers for example. A faster read speed will transfer images to your computer more rapidly also (depending on how the SD card is wired up to the computer, as a direct connection vs USB 2 vs FireWire 800 vs USB 3 will make a significant difference also, as will, potentially, your hard disk or SSD storage memory speed).
SDHC (Secure Digital High Capacity) Memory cards:
These are SD memory cards but with higher capacity. Unlike other memory cards the SDHC was invented with a maximum capacity of 32GB. Cameras that was made before the SDHC may not be recognisable to the device.
SDXC (Secure Digital ‘Xtra Capacity’) Memory Cards:
These are SD cards but with a higher capacity and faster processing speeds. These have the maximum capacity of 2TB (Terabytes). Similar to the SDHC the SDXC fits in a normal SD card slot.