The iron rake is suitable for all heavy soil types and the wooden rake for lighter soil types.
Raking is the final processing measure to produce a finely crumbly seed- or plant beds. The steel rake is definitely to be preferred on heavier and cloddy soils. Due to its own heaviness, it makes tillage much easier. The wooden rake is too light for these floors and there is also a risk, that the tines break off. It does a good job on the lighter soils and is suitable e.g. much better for raking the lawn than the iron rake.