If you want to check hotfixes, you should compare installed hotfixes on a master image with some other machine. Go ahead and use Compare-Object and this approach:
$machine1 = Get-HotFix -ComputerName server-master
$machine2 = Get-HotFix -ComputerName someother-pc–or-IP
Compare-Object -ReferenceObject $machine1 -DifferenceObject
$machine2 = Get-HotFix -ComputerName someother-pc–or-IP
Compare-Object -ReferenceObject $machine1 -DifferenceObject
$machine2 -Property HotfixID -IncludeEqual
