I have both, but I don't know the variety of my pieris. My MIL wanted to get rid of it because it kept over-
growing it's place. I would call it a relatively slow grower, but they can get large if left to grow. The spruce is a VERY slow grower. I bought mine about 6 years ago at about 18". They are now about 4 feet. They will get very tall though but it takes many years. My mother planted one in her yard about 25 years ago and I would guess its about 15-17 feet now. Hope it helps give you a little idea.