Gives you a way to compare 2 objects side by side to see what properties differ. The example shows how we could compare 2 user accounts from AD (arbitrarily picks the first 2 people called John from the directory for comparison)

Compare-ArrayItems.ps1

function Compare-ArrayItems {
	[CmdletBinding()]
	Param (
		[Parameter(Mandatory)]
		[PSObject[]]$ReferenceArray
		,
		[Parameter(Mandatory)]
		[PSObject[]]$DifferenceArray
	)
	# note: this treats the arrays as sets; i.e. doesn't care what position items are in within an array, or if the same item occurs multiple times
	$union = ($ReferenceArray + $DifferenceArray) | Sort-Object -Unique
	$union | ForEach-Object {
		$inA = $_ -in ($ReferenceArray)
		$inB = (!$inA) -or ($_ -in ($DifferenceArray))
		([PSCustomObject]@{
			Item = $_
			Compare = $(if ($inA -and $inB){0}else{if($inA){1}else{-1}})
			Reference = $inA
			Difference = $inB
		}) 
	}	
}

# get some example users
$a,$b,$ignoretail = Get-AdUser -filter "givenname -eq 'John'" -Properties MemberOf

# get their memberof info in a more readable format
$aGroups = $a.memberof | %{$_ -replace '^CN=(.*?),OU=.*','$1'}
$bGroups = $b.memberof | %{$_ -replace '^CN=(.*?),OU=.*','$1'}

# compare
Compare-ArrayItems $aGroups $bGroups | 
    Where-Object {$_.Compare -ne 0} | 
    Format-Table -AutoSize

Compare-ObjectProperties.ps1

function Compare-ObjectProperties {
	[CmdletBinding()]
	Param (
		[Parameter(Mandatory)]
		[PSObject]$ReferenceObject
		,
		[Parameter(Mandatory)]
		[PSObject]$DifferenceObject
	)
	$props = (@($ReferenceObject | Get-Member -MemberType Properties | Select-Object -ExpandProperty Name) + @($DifferenceObject | Get-Member -MemberType Properties | Select-Object -ExpandProperty Name)) | Sort-Object -Unique
	$props | %{
		([PSCustomObject]@{
			Property = $_
			Compare = $(if ($ReferenceObject."$_" -eq $DifferenceObject."$_") {0} else {try{@(-1,1)[$ReferenceObject."$_" -lt $DifferenceObject."$_"]}catch{'?'}})
			Reference = $ReferenceObject."$_"
			Difference = $DifferenceObject."$_"
		})
	}
}

$a,$b,$ignoretail = Get-AdUser -filter "givenname -eq 'John'" -Properties *
$colFormats = @(
    @{L='Property';   E={$_.Property};   W= 30},
    @{L='=';          E={$_.Compare};    W=  1},
    @{L='Reference';  E={$_.Reference};  W=100},
    @{L='Difference'; E={$_.Difference}; W=100}
)
Compare-ObjectProperties -ReferenceObject $a -DifferenceObject $b | 
    Where-Object{$_.Compare -ne 0} | 
    Format-Table $colFormats