The antonym for the phrase "am similar to" is "am dissimilar to" or "am different from." While being similar means having some commonalities, being dissimilar means being distinct or different. To be dissimilar is to not have any resemblance or relation to something else. It's about being unlike in various aspects like physical characteristics, behavior patterns, or ideologies. The word "dissimilar" could be used in contexts where one needs to differentiate between two things, and the word "different" could be used more informally. Hence, using appropriate antonyms for the word "am similar to" allows us to describe things in a more precise manner.