While "Green Giant" Thujas are known for being rather large and fast-growing, "Emerald Green" Thujas only grow 8 to 12 feet tall and 3 to 4 feet wide. They are better suited for smaller landscapes, will fit easier into tighter spaces such as around a driveway, and will even grow in containers. Another difference is their tolerance levels to temperature. "Green Giant" arborvitaes tolerate some snow and ice and temperatures down to -20 degrees Fahrenheit, but "Emerald Green" arborvitaes are much more cold resistant. Therefore, Thuja "Green Giants" will thrive in dry, southern areas where some other evergreens like the "Emerald Greens" may not.