• SPListItem.Update() is used to update all the values in SharePoint List Item including Modified Date, Modified By, Version fields
• 
  
• SPListItem.SystemUpdate() is used to update the values of the list item without modifying the Modified Date, Modified By and Version fields.
• 
  
• SPListItem.Update() . Event Receiver is fired in case if listitemupdated,listitemupdating  event is associated. 
• SPListItem.SystemUpdate() Event Receiver won't be fired in case if list item updated, listitemupdating  event is associated

Hope It will works fine. 

# Add the snapin, in case it's not already installed
Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue

$ver = (Get-PSSnapin microsoft.sharepoint.powershell).Version.Major
If ($ver -eq "15" )
    {
        Write-Output "SharePoint 2013 is installed"
        }
    elseif ($ver -eq "14")
    {
        Write-Output "SharePoint 2010 is installed"
        }
        else
        {
            Write-Output "Could not determine version of SharePoint"
            } 

$site = new-object Microsoft.SharePoint.SPSite("http://<Site URL>") #Change site URL#
    $web = $site.openweb()
    $list = $web.Lists["<List Name>"] #Get Field Details for specified list
   
    Write-Host "List Name: " $list.Title  ##Print List title
    Write-Host "------------------------------------------------------"
    Write-Host "Field Name | Field Title "
    Write-Host "------------------------------------------------------"        
   
    foreach ($field in $list.Fields) #Get all views in lists
    {
        Write-Host $field.Title " | " $field.Type -ForegroundColor Green #Write out each field (column)                        
       
    }  
    Write-Host "------------------------------------------------------"
    Write-Host " "

    $web.Dispose()
    $site.Dispose()

In this article, we retrieved the particular list properties in SharePoint Site.

#Declare the variable for below functions
$SiteCollectionURL="https://sharepointonline.sharepoint.com/sites/mysite"
$listName="Project list"


function GetSPFieldDetailsForList($SiteCollectionURL, $listName)
{
    $site = new-object Microsoft.SharePoint.SPSite($SiteCollectionURL) #Change site URL#
    $web = $site.openweb()
    $list = $web.Lists[$listName] #Get Field Details for specified list
   
    foreach ($view in $list.Views) #Get all views in lists
    {
        $spView = $web.GetViewFromUrl($view.Url) #Grab views URL
        Write-Host "List Name: " $list.Title  ##Print List title
        Write-Host "------------------------------------------------------"
        Write-Host "Field Name | Field Title "
        Write-Host "------------------------------------------------------"
        foreach ($spField in $spView.ViewFields) #Loop through all view URLs and get Fields (columns)
        {
            foreach ($field in $list.Fields) #Get all fields in lists
            {
                if($spField -eq $field.Title) #if field in lists equals field in views
                {
                    Write-Host $spField " | " $field.Type -ForegroundColor Green #Write out each field (column)                      
                }
            }
        }
        Write-Host "------------------------------------------------------"
        Write-Host " "
    }  
    $web.Dispose()
    $site.Dispose()
}