Shalom, shilohsfoal.
Veteran is right, though. Compare the sizes of the cities, Yahuwh-shameh vs. Yerushalayim haChadashah:
Ezekiel 48:8-22
8 "Bordering the territory of Judah from east to west will be the portion you are to present as a special gift. It will be 25,000 cubits wide, and its length from east to west will equal one of the tribal portions; the sanctuary will be in the center of it.
9 "The special portion you are to offer to the Lord will be 25,000 cubits long and 10,000 cubits wide. 10 This will be the sacred portion for the priests. It will be 25,000 cubits long on the north side, 10,000 cubits wide on the west side, 10,000 cubits wide on the east side and 25,000 cubits long on the south side. In the center of it will be the sanctuary of the Lord. 11 This will be for the consecrated priests, the Zadokites, who were faithful in serving me and did not go astray as the Levites did when the Israelites went astray. 12 It will be a special gift to them from the sacred portion of the land, a most holy portion, bordering the territory of the Levites.
13 "Alongside the territory of the priests, the Levites will have an allotment 25,000 cubits long and 10,000 cubits wide. Its total length will be 25,000 cubits and its width 10,000 cubits. 14 They must not sell or exchange any of it. This is the best of the land and must not pass into other hands, because it is holy to the Lord.
15 "The remaining area, 5,000 cubits wide and 25,000 cubits long, will be for the common use of the city, for houses and for pastureland. The city will be in the center of it 16 and will have these measurements: the north side 4,500 cubits, the south side 4,500 cubits, the east side 4,500 cubits, and the west side 4,500 cubits. 17 The pastureland for the city will be 250 cubits on the north, 250 cubits on the south, 250 cubits on the east, and 250 cubits on the west. 18 What remains of the area, bordering on the sacred portion and running the length of it, will be 10,000 cubits on the east side and 10,000 cubits on the west side. Its produce will supply food for the workers of the city. 19 The workers from the city who farm it will come from all the tribes of Israel. 20 The entire portion will be a square, 25,000 cubits on each side. As a special gift you will set aside the sacred portion, along with the property of the city.
21 "What remains on both sides of the area formed by the sacred portion and the city property will belong to the prince. It will extend eastward from the 25,000 cubits of the sacred portion to the eastern border, and westward from the 25,000 cubits to the western border. Both these areas running the length of the tribal portions will belong to the prince, and the sacred portion with the temple sanctuary will be in the center of them. 22 So the property of the Levites and the property of the city will lie in the center of the area that belongs to the prince. The area belonging to the prince will lie between the border of Judah and the border of Benjamin.
NIV
Rev 21:15-21
15 The angel who talked with me had a measuring rod of gold to measure the city, its gates and its walls. 16 The city was laid out like a square, as long as it was wide. He measured the city with the rod and found it to be 12,000 stadia in length, and as wide and high as it is long. 17 He measured its wall and it was 144 cubits thick, by man's measurement, which the angel was using. 18 The wall was made of jasper, and the city of pure gold, as pure as glass. 19 The foundations of the city walls were decorated with every kind of precious stone. The first foundation was jasper, the second sapphire, the third chalcedony, the fourth emerald, 20 the fifth sardonyx, the sixth carnelian, the seventh chrysolite, the eighth beryl, the ninth topaz, the tenth chrysoprase, the eleventh jacinth, and the twelfth amethyst. 21 The twelve gates were twelve pearls, each gate made of a single pearl. The great street of the city was of pure gold, like transparent glass.
NIV
Now, a "cubit" is normally about 18 inches, but if it is a royal cubit as was used for the pyramids in Egypt, it would be between 21 and 22 inches. Thus, Yahuwh-shameh will be 4500 cubits x 18 in/cubit x 1 ft/12 in = 6750 ft or as long as 4500 cubits x 22 in/cubit x 1/ft/12 in = 8250 ft. Since a mile is 5280 feet, this distance would not even be 2 miles in length.
A "stadios" (plural "stadia"), coming from the Roman measurement of a "stadium," is at least 582 feet! Today, it is generally agreed that the "stadium" was probably similar to today's measurement of a furlong at 660 feet, based on Roman mile markers. At 12,000 furlongs (stadia) on a side, this means that each side of Yerushalayim haChadashah would be at least ...
12,000 stadia x 582 ft/stadios x 1 mi/5280 ft = 1322.727 miles long! And, it is probably more like 12,000 stadia x 660 ft/stadios x 1 mi/5280 ft = 1500 miles long!
They are NOT the same city. The temporary city, Yahuwh-shameh, is not much bigger than the walls of the Old City of Jerusalem and not as big as the modern, sprawled-out metropolis of Jerusalem. The permanent city, Yerushalayim haChadashah, is MUCH bigger - bigger than any city has EVER been! It will cover an arc of the New Earth's surface of 1500 mi/24902 mi x 360 degrees = 21.685 degrees! That means that the middle gate of one side of the city is not even in the same time zone as the middle gate of the other side of the city! (It stretches out even farther from corner to opposite corner. It also towers above the New Earth's surface just as high, 1500 miles! Mount Everest is less than 5.5 miles high at 29,028 feet!)
In my opinion, this fact alone should convince one that the Millennium is different than the eternal state, and that the Millennium - stretching out just a little longer than the lifespan of Adam (950 years) and Metushelach (Methusaleh, 962 years) - is merely the first stage of eternity, a time for correcting all of mankind's problems before eternity proper begins, a time for the judgments of the wise Yeshua` haMelekh (Jesus the King) to be given and enemies to be subdued, until finally the last enemy, death, is finally defeated.