Common Coding Standards for Chinese Characters

Big5
The name of "Big5" was drawn up by five large computer markers in Taiwan that developed the de facto standard, also called industrial standard, in 1984. It contains 13,051 distinct Chinese characters, arranged in two levels by number of strokes and then by radical. It is also commonly used in Hong Kong.

Guo Biao (GB)

Stands for a series of standards issued by the government in Mainland China. The most commonly used computer coding standards is called GB2312-80, which is referred to as GB2313 or simply GB. The characters in GB2312-80 are arranged by two levels, the first is arranged by reading and the second is by radical then number of strokes.

ISO 10646
It is a coding standard developed by the International Organization for Standardization (ISO) to embrace characters of all major languages in the world. It contains about 27,484 Han characters (in ISO/IEC 10646-1:2000) and it unifies the Han character coding standards of Mainland China, Taiwan, Japan, Korean, and Vietnam. The ISO 10646 standard can be regarded as equivalent to the Unicode standard.

ISO 10646 GB 18030-2000 Big5
Characteristics Unified the Han character coding standards of some Asian counties, including all the characters in Big5 and GB
Internal code point assignment different from the ISO 10646 standard Only includes Traditional Chinese characters
Supported characters Both Simplified and Traditional Chinese characters can be displayed in the same interface Closely follow the character set of the ISO 10646 standard Only Traditional Chinese characters can be displayed in an interface
Number of characters About 27,000 Around 27,000 13,051
Commonly used areas All over the world Mainland China Taiwan, Hong Kong
Developer International Organization for Standardization (ISO) Government of Mainland China The five software developers in Taiwan

(The 3 Common Coding Standards for Chinese characters)