Why is -like not working but -match does? - powershell

Question

I got this script from here and it work for uninstalling an application, but only when -match is used instead of -like in the first 2 lines, even when I use the entire app name.
The app's name includes the version, so I'd like to wildcard the name in the script to support "MyApp 2.4.1", etc. Thanks!
$uninstall32 = gci "HKLM:\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall" |
foreach { gp $_.PSPath } | ? { $_ -like "MyApp*" } | select UninstallString
$uninstall64 = gci "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" |
foreach { gp $_.PSPath } | ? { $_ -like "MyApp*" } | select UninstallString
if ($uninstall64) {
$uninstall64 = $uninstall64.UninstallString -Replace "msiexec.exe","" -Replace "/I","" -Replace "/X",""
$uninstall64 = $uninstall64.Trim()
Write "Uninstalling..."
start-process "msiexec.exe" -arg "/X $uninstall64 /qb" -Wait
}
if ($uninstall32) {
$uninstall32 = $uninstall32.UninstallString -Replace "msiexec.exe","" -Replace "/I","" -Replace "/X",""
$uninstall32 = $uninstall32.Trim()
Write "Uninstalling..."
start-process "msiexec.exe" -arg "/X $uninstall32 /qb" -Wait
}

Answer 1

Get-ItemProperty produces an object, not a string. Check the DisplayName property instead of the object itself. You should also expand the uninstall string, so you don't need to use $uninstall64.UninstallString later.
$uninstall64 = gci "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" |
foreach { gp $_.PSPath } |
? { $_.DisplayName -like "MyApp*" } |
select -Expand UninstallString

Answer 2

Consider the following string " MyApp 2.3.4" while will look at the important difference between the two examples you refer to:
Like ? { $_ -like "MyApp*" }
Match ? { $_ -match "MyApp*" }
-Like is looking for a string starting with "MyApp" followed by anything. -Match is looking for the text "MyApp" followed by any character. The -Like would fail since there is a preceding space. -Match treats "MyApp*" as a regex string which looks for "MyApp" followed by any character. In this case it cares not about the space to it matches. I suspect the -match would fail if you changed it too ? { $_ -match "^MyApp*" } as the caret says start of string.
If you want -like to work in this case you should change it to ? { $_ -like "*MyApp*" }
Important
While I am correct about why your comparison was not working Ansgar answer addresses the reason this issue was happening to you in the first place.