Question about available firmwares

Hey guys, I dunno if this has been asked before or not but I did make a search about it and didn't find anything. I own a W995 and I was wondering what is the difference between these particular files:

W995_R1EA028_FS_APAC-ANZ-A_RED53
And
W995_R1EA028_FS_APAC-ANZ_RED53

W995_R1EA028_MAIN_GENERIC_HI_RED53
And
W995_R1EA028_MAIN_APAC_HI_RED53

Thank you for any answers you can provide me and I apologize if this has been asked before.

thanks for all