[ecfisa]

Hola jeremiselxi.

Código Delphi [-]
uses DateUtils; // necesario para DaysBetween
...
var
  d1, d2: Integer;
begin
  // 1)  usando DaysBetween
  d1:= DaysBetween(DateTimePicker1.Date, DateTimePicker2.Date);
  // 2)  usando resta
  d2:= Trunc(DateTimePicker2.Date - DateTimePicker1.Date);  
  Caption:= Format('%d %d',[d1, d2]);
end;

Saludos