What are the fundamental similarities and differences between lamarckism and darwinism?
Both darwinism and lamarckism are evolutionary theories as opposed to fixism, both admit the existence of processes that caused changes in the characteristics of the living beings in the past.
They have though different explanations for those changes. The Lamarckism combines the law of use and disuse with the law of the transmission of acquired characteristics to explicate the changes. The Darwinism defends the action of the natural selection.