What's the difference between m68k-coff and m68k-elf ABI?

[clifftsai]

Hi:
    When I build the m68k cross development 
according
      Instructions from 
Cygnus's Website.The instrucions tell
    us to build m68k tool as 
m68k-coff.
    But when I look into the 
glibc/sysdeps/m68k/elf.
    The Start.s is for m68k-elf ABI.Why?How 
about Start.s
    for coff.
    And if I use m68k-coff 
or m68k-arm,what should I modified?
    
    Thanks 
    Cliff