You are correct, Freedom is a very large ship and 18 years ago was the largest cruise ship afloat. But the 76' difference in length is only one rather insignificant measure in the difference in size with Symphony. Symphony has a gross tonnage of 228,000 tons with a maximum passenger capacity of over 6,600 guests. Freedom has a gross tonnage by comparison of 156,000 tons and a maximum passenger capacity of just over 4,500 guests.
The differences are rather significant IMO. Symphony is quite a bit larger by those measures. Although they share many of the same venues, the layout and design of Symphony is completely different from Freedom.
I only say this for the OP as by comparison, IMO they are apples to oranges.