I believe the Thuja grows at a faster rate, usually 2 to 3 feet a year. I have planted others bought at 6' from another company with few branches and they have grown about 2' per year and are finally starting to fill out. The ones from Home Depot are very full and about 4' when the arrive. I have bought several last year and this year....very satisfied!
Mine was 44-45" (less than the minimum 48" advertised)