Question: are algae and seaweed the same thing?
Answer: Seaweeds are a group of algae, and have some special characteristics viz. macroscopic, multi-cellular, benthic, and marine. ... All the seaweed species are autotrophic, whereas some algal species rely on other external food materials. Algae inhabit both freshwater and marine waters, while seaweeds inhabit only seawaters.