Latin characters take 1 byte each and unicode characters take 2 bytes for each character.
Teradata has a 64000 byte limit for char data types.
So when you declare a column to be LATIN, it can hold upto 64000 characters(1 byte each, so 64K characters, 64KB limit).
When you declare it as UNICODE, it can hold upto 32000 unicode characters(2 bytes each, so 32K characters,64KB limit)
Teradata max limits,
CHAR(64000) CHARACTER SET LATIN
CHAR(32000) CHARACTER SET UNICODE
Oracle CHAR type holds latin characters. upto 2000 characters (size 2000 bytes)
Oracle NCHAR type holds unicode characters. upto 2000 characters(size 4000 bytes)