I will list and describe the form factors of SD (Secure Digital) memory cards:
SD (up to 4 GB)
SDHC (Secure Digital High Capacity, up to 32 GB)
SDXC (Secure Digital eXtended Capacity, up to 2 terabytes)
SDUC (Secure Digital Ultra Capacity, up to 128 TB)
microSD
miniSD
miniSDHC
UHS I and UHS II have increased write speed
List of SD card classes:
SD Class 2 (write speed of at least 2 MB/s)
SD Class 4 (write speed of at least 4 MB/s)
SD Class 6 (write speed of at least 6 MB/s)
SD Class 10 (write speed of at least 10 MB/s)
SD Class 16 (write speed of at least 16 MB/s)
Ultra High Speed (UHS) Class 1 (write speed of at least 10 MB/s)
Ultra High Speed (UHS) Class 3 (write speed of at least 30 MB/s)