What are the two types of looms?

As a cryptocurrency and finance practitioner, I'm curious to understand the nuances within the realm of blockchain technology. Could you elaborate on the two types of looms that exist in the context of this domain? I've heard references to looms in discussions regarding the architecture and functionality of blockchains, but the specific distinction between them remains unclear to me. Are these looms related to consensus mechanisms, network topology, or some other fundamental aspect of blockchain technology? I'd appreciate a concise yet comprehensive explanation that sheds light on this enigmatic topic.