The Internet of Things (IoT) is rapidly spreading across a wide range of applications because it is a critical technology for overcoming interoperability and heterogeneity barriers in many applications. IoT is increasingly being deployed in a distributed setting because of the vast number of devices and the physical dispersal of many use cases. Because IoT devices are often resource-restricted, this scattered implementation style exposes devices to unprecedented privacy and security risks. Distributed Ledger Technologies (DLT), such as blockchain, appear to be a perfect solution to integrate with IoT systems to overcome these challenges thanks to its key pillars: decentralisation, transparency and immutability. The use of blockchain in IoT has been widely examined, and the findings demonstrate how blockchain can be a crucial enabler for IoT. However, blockchain consensus mechanisms are often very energy-intensive, whereas IoT devices are resource-constrained with limited computational power, storage and energy. Therefore, as the literature emphasises, new consensus algorithms could solve most of these issues associated with blockchain technology. Holochain is an emerging DLT that promises to provide blockchain's key benefits and eliminate problems that come with it, such as consensus algorithms and the requirement to maintain a globally synchronised ledger. It has already attained the research community's awareness due to its potential to replace blockchain as a distributed computing solution. This paper compares blockchain and holochain in the context of IoT, considering scalability, availability, security and resource requirements.