Noodles are more sponge like. I've used 1 that when squeezed, it expelled water out of it. I've also held a waterlogged noodle. It was much heavier then a non-waterlogged noodle. Even left to float in a pool, where there isnt freeze thaw cycles, they get heavier, so soaking up water.
More then 1 Starcraft guy tested noodles. Most over estimate the dead weight a noodle will float (primary reason not to use them), when exposed to water, they soak it up just (reason 2 not to use them) and they arent an effiecent shape to maximize flotation value.