how are kelp and seaweed similar?

Answer:

Both kelp and seaweed are types of marine algae. They are photosynthetic organisms that grow in aquatic environments and play important roles in marine ecosystems, such as providing habitats for marine life and contributing to the ocean's oxygen - production.

Brief Explanations:

Kelp is a large brown seaweed. Seaweed is a general term for marine algae. Their biological nature as algae links them.