There are four standards for capacity:

SD SD standard – Up to 2GB SD memory card using FAT 12 and 16 file systems
SDHC SDHC standard – over 2GB-32GB SDHC memory card using FAT32 file system
SDXC SDXC standard – over 32GB-2TB SDXC memory card using exFAT file system
SDUC SDUC standard – over 2TB-128TB SDUC memory card using exFAT file system
SD Standard SDHC Standard SDXC Standard SDUC Standard
Capacity up to 2GB more than 2GB

up to 32GB

 more than 32GB

up to 2TB

 more than 2TB

up to 128TB
File System FAT 12, 16 FAT 32 exFAT exFAT
SD Logo SD SDHC SDXC SDUC
Form Factor Size SD 32 x 24 x 2.1 mm
microSD 11 x 15 x 1.0 mm

Speed Classes
 NS mode C2, C4, C6
HS mode C2, C4, C6, C10,

V6, V10
UHS-I

mode

 — C2, C4, C6, C10

U1, U3

V6, V10, V30
UHS-II

mode

 — C4, C6, C10

U1, U3

V6, V10, V30, V60, V90
UHS-III

mode

 — C4, C6, C10

U1, U3

V6, V10, V30, V60, V90