PowerShell Compare-Object misbehaving or objects not compatible for comparison?

I am trying to compare the names of noteproperty items in two different variables created by different means
The first is a list of columns in an SQL Server database, the second comes from ConvertFrom-Json
I have tried to make the objects compatible for comparison with each other by using several different techniques but every method i try fails.

Below is the best working example of code i have been able to come up with but the results it gives are not correct.

In the below example, just before the compare-object command the variables equal:

C:\Users\Stuart\Desktop\Amy-EVA3 [master ≡ +0 ~1 -0 !]> $JournalObjectNotePropertyList

Name                      
----                      
event                     
FuelLevel                 
FuelUsed                  
JumpDist                  
StarPos                   
StarSystem                
SystemAllegiance          
SystemEconomy             
SystemEconomy_Localised   
SystemGovernment          
SystemGovernment_Localised
SystemSecurity            
SystemSecurity_Localised  
timestamp   

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C:\Users\Stuart\Desktop\Amy-EVA3 [master ≡ +0 ~1 -0 !]> $AmyEventNotePPropertyList

Name     
----     
event    
event_id 
timestamp

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yet the result coming from the following Compare-Object command is:

C:\Users\Stuart\Desktop\Amy-EVA3 [master ≡ +0 ~1 -0 !]> Compare-Object -ReferenceObject $JournalObjectNotePropertyList -DifferenceObject $AmyEventSQLColumns -PassThru -IncludeEqual

Name                       SideIndicator
----                       -------------
event                      ==           
FuelLevel                  <=           
FuelUsed                   <=           
JumpDist                   <=           
StarPos                    <=           
StarSystem                 <=           
SystemAllegiance           <=           
SystemEconomy              <=           
SystemEconomy_Localised    <=           
SystemGovernment           <=           
SystemGovernment_Localised <=           
SystemSecurity             <=           
SystemSecurity_Localised   <=           
timestamp                  <=   

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As you can see timestamp exsits on both sides of the compare yet the result does not agree. event_id exsits on one side without the other yet is not listed.  event is correct as it appears on both.

Can anyone explain what might be happening and how to get the required result?

if ($SQLCredentials -eq $null)
{
    $SQLCredentials = Get-Credential
}
$SQLPassword = $SQLCredentials.GetNetworkCredential().password
$Debug = 1
$SQLServer = 'sql.database.windows.net'
$SQLdbName = 'mydb'
$SQLEventTableName = 'event'  
$SQLConnectionString = 'Data Source=' + $SQLServer + ';Initial Catalog=' + $SQLdbName + ';Integrated Security=False;User ID=' + $SQLCredentials.UserName + ';Password=' + $SQLPassword
$SQLConnection = New-Object System.Data.SqlClient.SqlConnection ($SQLConnectionString)
$SQLConnection.Open()
if ($SQLConnection.State -eq [System.Data.ConnectionState]::Open)
{
	if ($Debug -eq 1)
	{
		Write-Host -ForegroundColor Green 'Database connection successful !!!'
	}
}

$SQLCommandQuery = "SELECT COLUMN_NAME FROM " + $SQLdbName + ".INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '" + $SQLEventTableName + "'"

if ($SQLCommandQuery)
        {
		    $SQLCommand = New-Object system.Data.sqlclient.SqlCommand
            $AmyEventSQLColumns = New-Object psobject
		    $SQLCommand.connection = $SQLConnection
		    $SQLCommand.commandtext = $SQLCommandQuery
		    $SQLResponse = $SQLCommand.ExecuteReader()
            while ($SQLResponse.Read())
            {
                Add-Member -InputObject $AmyEventSQLColumns -MemberType NoteProperty -Name ($SQLResponse.GetValue($1)) -value "" > $null
            }
        }

$JSONContents = gc .\SmallJournal.json
$ErrorActionPreferenceBefore = $ErrorActionPreference
$ErrorActionPreference = "SilentlyContinue"
$JSONContents = $JSONContents.Replace(':true,', ':"1",')
$JSONContents = $JSONContents.Replace(':false,', ':"0",')
$ErrorActionPreference = $ErrorActionPreferenceBefore
$JournalObjectNotePropertyList = ($JSONContents | ConvertFrom-Json | gm -MemberType NoteProperty | Select-Object Name)
$AmyEventNotePPropertyList = $AmyEventSQLColumns | gm -MemberType NoteProperty | Select-Object Name

Compare-Object -ReferenceObject $JournalObjectNotePropertyList -DifferenceObject $AmyEventSQLColumns -PassThru -IncludeEqual

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My ultimate goal is to check a the database for columns that will require adding before a object derived from ConvertFrom-Json is added to a row.  Every noteproperty obviously has to have a place in the database and so to eliminate errors i need to create those columns in advance.  This part of the script is meant to compare what is needed and what is there already and therefore creating a list of what we don't have - this will get passed to an SQL ALTER table command to add the columns.

Extra information follows:

C:\Users\Stuart\Desktop\Amy-EVA3 [master ≡ +0 ~1 -0 !]> $AmyEventNotePPropertyList |gm


   TypeName: Selected.Microsoft.PowerShell.Commands.MemberDefinition

Name        MemberType   Definition                    
----        ----------   ----------                    
Equals      Method       bool Equals(System.Object obj)
GetHashCode Method       int GetHashCode()             
GetType     Method       type GetType()                
ToString    Method       string ToString()             
Name        NoteProperty string Name=event   

C:\Users\Stuart\Desktop\Amy-EVA3 [master ≡ +0 ~1 -0 !]> $JournalObjectNotePropertyList |gm


   TypeName: Selected.Microsoft.PowerShell.Commands.MemberDefinition

Name          MemberType   Definition                    
----          ----------   ----------                    
Equals        Method       bool Equals(System.Object obj)
GetHashCode   Method       int GetHashCode()             
GetType       Method       type GetType()                
ToString      Method       string ToString()             
Name          NoteProperty string Name=event             
SideIndicator NoteProperty string SideIndicator===  

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