This paper explores the differences between major social media platforms and how they influence the formation of echo chambers and information spreading. The study analyzes over 100 million pieces of content from Gab, Facebook, Reddit, and Twitter related to controversial topics such as gun control, vaccination, and abortion. The research quantifies echo chambers through two main factors: homophily in interaction networks and bias in information diffusion toward like-minded peers. The results show that users tend to form homophilic clusters on Facebook and Twitter, where interactions are dominated by similar opinions. A direct comparison of news consumption between Facebook and Reddit reveals higher segregation on Facebook. The study also finds that information diffusion is biased toward users with similar leanings on some platforms, such as Facebook and Twitter, while this effect is absent on Reddit and Gab. The paper defines echo chambers as environments where users' opinions are reinforced through interactions with like-minded peers. It introduces an operational definition of echo chambers, focusing on two key elements: the individual leaning of users and the structure of their social interactions. The study uses these elements to assess the presence of echo chambers by analyzing homophily and information diffusion bias. The analysis shows that platforms with feed algorithms, such as Facebook and Twitter, favor the emergence of echo chambers. In contrast, platforms like Reddit and Gab, which do not have such algorithms, show less polarization. The study also highlights the role of selective exposure and confirmation bias in the formation of echo chambers on social media. Overall, the research provides insights into how different social media platforms influence the formation of echo chambers and the spread of information. The findings suggest that the structure and design of social media platforms significantly impact the dynamics of online interactions and the formation of polarized communities.This paper explores the differences between major social media platforms and how they influence the formation of echo chambers and information spreading. The study analyzes over 100 million pieces of content from Gab, Facebook, Reddit, and Twitter related to controversial topics such as gun control, vaccination, and abortion. The research quantifies echo chambers through two main factors: homophily in interaction networks and bias in information diffusion toward like-minded peers. The results show that users tend to form homophilic clusters on Facebook and Twitter, where interactions are dominated by similar opinions. A direct comparison of news consumption between Facebook and Reddit reveals higher segregation on Facebook. The study also finds that information diffusion is biased toward users with similar leanings on some platforms, such as Facebook and Twitter, while this effect is absent on Reddit and Gab. The paper defines echo chambers as environments where users' opinions are reinforced through interactions with like-minded peers. It introduces an operational definition of echo chambers, focusing on two key elements: the individual leaning of users and the structure of their social interactions. The study uses these elements to assess the presence of echo chambers by analyzing homophily and information diffusion bias. The analysis shows that platforms with feed algorithms, such as Facebook and Twitter, favor the emergence of echo chambers. In contrast, platforms like Reddit and Gab, which do not have such algorithms, show less polarization. The study also highlights the role of selective exposure and confirmation bias in the formation of echo chambers on social media. Overall, the research provides insights into how different social media platforms influence the formation of echo chambers and the spread of information. The findings suggest that the structure and design of social media platforms significantly impact the dynamics of online interactions and the formation of polarized communities.