Yes you are.

Information is power. The more you know the more you can make an informed decision.

In a nut shell, 631 is not heat treated so the tubes are not as thin as 853 which is. The thinner 853 tubes will be lighter but more flexable. Some builders (but not many) balance these two factors - for example, using a larger diameter thin tube in place of a thicker but smaller diameter one. The devils in the details which make the comparison very difficult without knowing which exact tubes are going to be used.