Final answer:
Lamarck believed in the inheritance of acquired traits, while Darwin believed that traits are passed down through genes.
Step-by-step explanation:
Lamarck believed that the use or lack of use of body parts enables individuals to develop certain traits that can be passed on to their offspring, while Darwin believed that species are fixed forms that do not change.
Lamarck theorized that traits acquired in an individual's lifetime can be inherited by their offspring in an attempt to improve. He also proposed that traits in offspring are a blend of traits from both parents.
In contrast, Darwin disagreed with Lamarck's theory and instead proposed that traits are passed down through the genes. He believed that individuals more fit to their environment are more likely to survive, reproduce, and pass on their genes.