It's always beneficial to try it yourself rather than continuously asking.
To see the difference run this quick sample:
Code:
Option Explicit

Private Type POINTAPI
    X As Long
    Y As Long
End Type

Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long

Private Sub Form_Load()
    Timer1.Interval = 100
    Timer1.Enabled = True
End Sub

Private Sub Timer1_Timer()
Dim pt As POINTAPI

    GetCursorPos pt
    
    Label1.Caption = "VB6 default: " & pt.X * Screen.TwipsPerPixelX
    Label2.Caption = "API Default: " & pt.X

End Sub
But to answer your question directly - VB's default scalemode is set to Twips and APIs return Pixels so you need to convert unless you set ScaleMode to Pixels as well.