Minecraft wiki entry for Spruce, associated text: A regular variant with a height between 5-12. The leaves tend to grow in discrete rows rather than the more spherical arrangement of oaks and birch trees. In Bedrock Edition, only this variant can be grown using saplings.
A fairly tall variant of spruce trees that generate in a matchstick style, with only a few leaves at the top.
A short variant in which the leaves are arranged in a roughly octahedral shape, similar to a lollipop.
A large 2×2 variant that generates in the old growth taiga biomes and can be grown from spruce saplings arranged in a 2×2 square, with or without bone meal. They are commonly called "redwoods" or "mega spruce trees".
These spruce trees have few leaves, concentrated at the top. Mega spruce trees with leaves only at the top can be found in old growth pine taiga, but not old growth spruce taiga (which has trees that have a lot of leaves on them).
The northwest block of the top layer of the 2×2 mega spruce tree trunk is always taller than the other three blocks.
A large 2×2 variant that generates in the old growth spruce taiga biome which has a lot more leaves than the other 2×2 spruce tree. In Bedrock Edition, only this variant can be grown using saplings.
A short 1×1 variant that generates on the sides of mountains, that has a few leaves, and appears to be 4-5 blocks tall.