Collecting from water is good because there will less tannins leached from the wood to deal with, so there will less soaking.
But, when you collect from water you need to be careful not to add a parasite or other water born organism that could harm your fish.
This is why you will either need to boil or bleach whatever you collect. If you choose to bleach be sure all traces of bleach has been removed before you add it to the tank.
Collecting dry or dead, has to be soaked for a lot longer to remove the natural tannin in the wood. And to water log the pieces so that they don't float.
I never put any kind of "green" wood in my tanks. Because some tree saps can be toxic to fish in the confines of an aquarium.
"Green" wood would be live or fresh cut trees.