Advantages of G4.1.3 & G4.1.5 over G4.1

Hi there:

I'm running my GRASS4.1 under Linux withour problem and Now,
looking for the FTP site, I saw that exist some kind of
upgrade (4.1.3 & 4.1.5). What's the advantages of this
new version in relation to my version?

Other question: What's the diferences between
        the files prefixed grassa* to linuxg.a*

ThanX for all help, miltinho

Milton@nimbus.dpi.inpe.br