https://flatassembler.net/docs.php?article=fasmg говорит нам:
What is flat assembler g?
It is an assembly engine designed as a successor of the one used in flat assembler 1, one of the recognized assemblers for x86 processors. This is a bare engine that by itself has no ability to recognize and encode instructions of any processor, however it has an ability to become an assembler for any CPU architecture. It has a macroinstruction language that is substantially improved compared to the one provided by flat assembler 1 and it allows to easily implement instruction encoders in form of customizable macroinstructions. This approach has a great flexibility at the cost of performance.
Т.е. fasm g -- это ассемблерный движок, нацеленный на то, чтобы стать ассемблером для любой архитектуры за счёт использования встроенного языка обработки макросов.
Т.е. как будто бы ответы на твои вопросы -- "не зависит", "отдельный", "предназначен для того же и большего".
Простой
