What are rules for whether or not using ^ to point to value?

Below is a simple example of using pointer in delphi.

Type

TRecord1 = Record
field1 : String;

end; 

procedure TForm1.Button2Click(Sender: TObject);
var
   Rec : TRecord1;
   Ptr: ^TRecord1;

begin
   Rec.field1:= 'field1';
   Ptr := @Rec;
   memo1.Lines.Add (Ptr^.field1); 
   memo1.Lines.Add (Ptr.field1); // it also works.

 end;

In such case, Ptr^ and Ptr both work. It seems delphi is to allow user more flexibility in pointing to the value. But just by reading the two lines, they are syntactically different and may mean differently. In such case both work. But my question is:

1. how can a user know in other situations where ^ can or can not be omitted or, where with ^ or without ^ means the same or differently?
2. What are those situations ? Examples will be appreciated.
3. Why? (Optional)

Thanks a lot in advance.