I got different result using 'show character set' and 'select * from information_schema.character_sets'

[Carl Wang]

show character set;
SELECT * FROM information_schema.CHARACTER_SETS;

The two sql will give different 'DEFAULT_COLLATE_NAME' for utf-8

The first is 'utf8mb4_general_ci'
The second is 'utf8mb4_0900_ai_ci'

And when i use
set names utf8mb4, collation_connection will be set to utf8mb4_general_ci

And when i use
set character_connection='utf8mb4', collation_connection will be set to utf8mb4_0900_ai_ci.

Why cause this phenomenon?