Hello and wellcome to the forum,
The Hiware object file format is more or less obsolete and supported only for legacy reasons by Freescale tools. A number of features are not available if using this object file format. As for the ELF absolute file, this is the "executable" file of your application. All the relocations are solved and the file is ready to be downloaded on the board/simulator. It is generated either by the linker or directly by the assembler. If you are using the assembler to generate the absolute file you will learn that you are not allowed to have any kind of relocatable code/data in your assembly file, meaning that the assembler must be able to precisely determine the memory location of every symbol (i.e. you have to put everything under ORG directives). As far as I remember CW ships with absolute assembly examples, you can use them as reference.
Hopefully this answers your question. If you are referring to the file format itself, it follows the ELF standard: http://refspecs.freestandards.org/elf/elf.pdf.
