SPEAR:
A spear is a pole weapon used for hunting and war, consisting of a shaft, usually of wood, with a sharpened head. The head may be simply the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be of another material fastened to the shaft, such as obsidian or bronze. The most common design is of a metal spearhead, shaped like a triangle or a leaf.
LANCE: While it could still be generally classified as a spear, the lance tends to be larger - usually both longer and stouter and thus also considerably heavier, and unsuited for throwing, or for the rapid thrusting, as with an infantry spear. Lances did not have spear tips that (intentionally) broke off or bent, unlike many throwing weapons of the spear/javelin family, and were adapted for mounted combat. They were often equipped with a vamplate, a small circular plate to prevent the hand sliding up the shaft upon impact.
I would argue they are not the same.
A bamboo spear (as above) and a bamboo lance would be the same thing, except that the lance would "often" have a vamplate.