I place the item found on sheet 2 but weren't on Sheet 1 and the end of the
list.  Try the code.

Sub combinesheets()

With Sheets("Sheet1")
  LastRowSh1 = _
     .Cells(Rows.Count, "A").End(xlUp).Row
  Set Sh1Range = .Range(.Cells(1, "A"), _
     .Cells(LastRowSh1, "A"))
End With
With Sheets("Sheet2")
  LastRowSh2 = _
     .Cells(Rows.Count, "A").End(xlUp).Row
  Set Sh2Range = .Range(.Cells(1, "A"), _
     .Cells(LastRowSh1, "A"))

  For Each cell In Sh2Range
     Set c = Sh1Range.Find(what:=cell, _
        LookIn:=xlValues)
     If Not c Is Nothing Then
        c.Offset(0, 1) = cell
     Else
        Sheets("Sheet1"). _
           Cells(LastRowSh1 + 1, "B") = _
           cell
           LastRowSh1 = LastRowSh1 + 1
     End If
 
  Next cell
End With

End Sub