Installpatchset does not work under Live updater

Hi,

When performing a patch on my solaris 10 server, i used LU as below.

Firstly created an LU boot environment.
Later when tried to patch the latest LU boot environment using ./installpatchset command, it gives an error message saying "The patch you are trying to install is already installed". But when executed using LUUPGRADE command, it worked and finally got a patch applied successfully message.

Could anyone please help me in understanding the difference in installpatchset and luupgrade and why patch was not applied using installpatchset and was applied when used luupgrade.

Thanks in advance.
Rocky C:)

Perhaps installpatchset does not see/accomodate/survive the mirrored os files and related configuration change undo; it's not what they say to use:
BigAdmin Sun Docs: How To Use Solaris Live Upgrade to Install Patches

What hardware is this exactly?

solaris 5.10 Generic_147441-27 i86pc i386 i86pc