Using contradicting parameters in Powershell

For my lab i'm trying to do some automation while trying to get better at Powershell in the mean time. Currently I'm use the two functions pasted below:

#Set a new hostname for a local virtual machine.
function New-VmHostname ($VmHostname, $NewComputerName, $credential) {
    Invoke-Command -VMName $VmHostname {
        Rename-Computer -NewName $using:NewComputerName -Force} -Credential $credential
}

#Set a new hostname for a remote machine.
function New-RemoteHostname ($RemoteHostname, $NewComputerName, $credential) {
    Invoke-Command -ComputerName $RemoteHostname {
        Rename-Computer -NewName $using:NewComputerName -Force} -Credential $credential   
}

Now I'm trying to write a function to be able to incorporate both functions above. Something like this:

#Set a new hostname for a lab machine
function New-Hostname {
    # Parameter help description
    Param(
        [Parameter(Position=0,
            Mandatory=$True,
            ValueFromPipeline=$True)]
        [string]$VmName,
        [Parameter(Position=1,
            Mandatory=$True,
            ValueFromPipeline=$True)]
        [string]$NewComputerName,
        [Parameter(Position=2,
            Mandatory=$True,
            ValueFromPipeline=$True)]
        [ValidateSet("Remote","VM")]
        [string]$RemoteSessionType
    )

    # Do stuff

}

What I want is for the function to have a parameter, $RemoteSessionType, to decide if the cmdlet downline uses the -VMName or uses the -ComputerName parameter. I can't seem to figure out how though.