임시변수로 클릭하기 전에 값을 기억해 뒀다가 값이 변하는 시점에서 비교해서 처리하면 될꺼 같은데요..

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, RXSpin;

type
  TForm1 = class(TForm)
    RxSpinEdit1: TRxSpinEdit;
    procedure RxSpinEdit1Change(Sender: TObject);
  private
    { Private declarations }
    procedure OnUpClick;
    procedure OnDownClick;
  public
    { Public declarations }
  end;

type
  TDirection = (rxsDOWN, rxsUP)

var
  Form1: TForm1;
  OldValue: Extended = 0;
  Direction: TDirection = rxsDOWN;

implementation

{$R *.DFM}

procedure TForm1.OnDownClick;
begin
  //To DO
end;

procedure TForm1.OnUpClick;
begin
  //To Do
end;

procedure TForm1.RxSpinEdit1Change(Sender: TObject);
begin
  if OldValue < RxSpinEdit1.Value then begin
    Direction := rxsUP;
    OnUpClick;
  end
  else begin
    Direction := rxsDOWN;
    OnDownClick;
  end;
  OldValue := RxSpinEdit1.Value;
end;

end.