I am using the Get-ChildItem cmdlet with the -Recurse parameter to enumerate all files and directories in a specific path.
If I run : (Get-ChildItem -Path $Path -Recurse | Where-Object -Property Attributes -Value Directory -EQ).Directory, it returns $null.
If I access this same Directory property on a file object, this returns the relative path to the search path.
Why isn't the same behaviour observed with a directory object ?
The behavior differs because it's a different kind of object.
Files are represented by FileInfo objects (which happen to have a Directory property), whereas directories are represented by DirectoryInfo objects (which do not happen to have such a property, but instead has a Parent property for the same purpose).
You can use Get-Member to discover these output types and their members:
Get-ChildItem -Path $Path -Recurse |Get-Member
If you just want the path to the parent directory, use Select-Object with Split-Path:
Get-ChildItem -Path $Path -Recurse |Select Name,@{Name='ParentPath';Expression={ $_.FullName |Split-Path -Parent }}
It's worth noting that PowerShell's provider subsystem attaches an ETS property named PSIsContainer to indicate whether a provider item is a container type (eg. a directory) or a leaf (eg. a file), so you don't need to inspect the Attributes property:
Get-ChildItem |Where-Object PSIsContainer -eq $true
The file system provider also exposes two parameters to Get-ChildItem with which you can filter up front:
Get-ChildItem -Directory # get only directories
Get-ChildItem -File # get only files