For comparison purposes you could simply use TypeOf.
If TypeOf entEntity Is Line Then
' Some code
End If
Note that Autodesk.AutoCAD.DatabaseServices must be imported
to use the Line type directly.
If you want the name of the entity without comparison then you could do this:
Dim strName as String
strName = entEntity.GetType.ToString
That will return something like "Autodesk.AutoCad.DatabaseServices.Line"
Dim strTypes() As String
strTypes= entEntity.GetType.ToString.Split(".")
strName = strTypes(strTypes.GetUpperBound(0))
That will return just "Line"