Why are CAT SHA1 hashes different than SHA1 hashes for PE files?

HashMismatch.ps1

Install-Module -Name PSScriptAnalyzer -RequiredVersion '1.11.0' -Force
$ModuleInfo = Get-Module -ListAvailable -Name PSScriptAnalyzer | ? { $_.Version -eq '1.11.0' }
$ModuleDir = Split-Path -Parent $ModuleInfo.Path
# C:\Program Files\WindowsPowerShell\Modules\PSScriptAnalyzer\1.11.0 for me

$NewtonsoftPath = "$ModuleDir\Newtonsoft.Json.dll"
$ManifestPath = "$ModuleDir\PSScriptAnalyzer.psd1"

# Requires Win 10 Enterprise to use the ConfigCI cmdlets
$ModuleFileInfo = Get-SystemDriver -UserPEs -NoShadowCopy -ScanPath $ModuleDir -PathToCatroot $ModuleDir

$NewtonsoftPath, $ManifestPath | % {
    $CurrentFile = $_
    $HashInfo = Get-FileHash -Algorithm SHA1 -Path $CurrentFile
    $FileInfo = $ModuleFileInfo | ? { ($_.FriendlyName -eq $CurrentFile) -and ($_.UserMode -eq $True) }

    # Get-FileHash uses the System.Security.Cryptography.SHA1CryptoServiceProvider class to calculate the hash
    # Get-SystemDriver uses CryptCATAdminAcquireContext2 w/ "SHA1" and CryptCATAdminCalcHashFromFileHandle2 to calculate the hash

    [PSCustomObject] @{
        GetFileHashHash = $HashInfo.Hash
        GetSystemDriverHash = $FileInfo.Hash
        Equal = $HashInfo.Hash -eq $FileInfo.Hash
        FilePath = $CurrentFile
    }
}

# Why do the hashes match for PSScriptAnalyzer.psd1 but not Newtonsoft.Json.dll?!?
# The hashes appear to differ when the file is a PE (EXE, DLL, etc.). Why is that?

This fact was used about 10-13 years ago (back when Authenticode signatures were all the hotness) to change binaries with overlaid executable data as part of the "Security Directory" which was not subject to the signing check. Certain tools such as WinZip self-extractors for example were then vulnerable to extracting the malicious code or executing the malicious overlaid data.