$vms = @()

$foo = New-Object -TypeName PSObject
$foo | Add-Member -MemberType NoteProperty -Name "Name" -Value "Host1"
$foo | Add-Member -MemberType NoteProperty -Name "OSDisk" -Value "64 GB"
$vms += $foo

$bar = New-Object -TypeName PSObject
$bar | Add-Member -MemberType NoteProperty -Name "Name" -Value "Host2"
$bar | Add-Member -MemberType NoteProperty -Name "OSDisk" -Value "64 GB"
$bar | Add-Member -MemberType NoteProperty -Name "DataDisk1" -Value "128 GB"
$vms += $BAR

$vms[0] | ft
$vms[1] | ft
$vms | ft




PS C:\> $vms[0] | ft

Name  OSDisk
----  ------
Host1 64 GB


PS C:\> $vms[1] | ft

Name  OSDisk DataDisk1
----  ------ ---------
Host2 64 GB  128 GB


PS C:\> $vms | ft

Name  OSDisk
----  ------
Host1 64 GB
Host2 64 GB


Name  OSDisk  DataDisk1
----  ------  ----------
Host1 64 GB
Host2 64 GB    128 GB