Attitudes of distrust and paranoia toward scientific and political institutions are increasingly identified as major troubles in online communication and often lumped together under the umbrella term of conspiracy theories. However, this term encompasses two distinct communication practices that deserve to be distinguished. Traditional conspiratorial thinking adopts pseudo-scientific arguments, while newer manifestations lack coherent theories, promoting trolling, and antagonism. We argue that these strands align with different types of digital communications and are supported by different technical infrastructure and cultures of use, with classic conspiracy theories prevalent in early online venues and “conspiracies-without-theory” more common on social media. By comparing the Flat Earth Society’s Internet forum and its subreddit, we highlight their stark differences. The forum prioritizes pseudo-scientific discourse, while the subreddit fosters confrontational antagonism and unmoderated escalation. Recognizing these distinctions is vital for understanding their communicative profoundly different nature and developing targeted strategies to address them effectively.