<human>:  What is the difference between a Colorado blue spruce and a Norway spruce?
<bot>: The Colorado blue spruce is a thick, pyramidal evergreen tree with long, bright blue-green needles, while the Norway spruce is a cone-shaped evergreen tree with shorter, dark green needles. The Colorado blue spruce is also more tolerant of dry, windy conditions and can be pruned to create a symmetrical look, while the Norway spruce is less tolerant of extreme conditions and cannot be pruned to create an attractive shape.