The Internet of Things (IoT) has garnered significant attention from people with growing changes in human life over the last few years. IoT is a network of a group of smart devices that use sensors to collect information and conduct events in their environments. The information can then be shared on the Internet. IoT uses a range of technologies and finds various applications such as smart homes, environmental monitoring, and healthcare. In this paper, we conducted a comparative study to analyze the difference between two technologies-Wireless Sensor Networks (WSNs) and Radio Frequency Identification (RFID). It is pertinent to note that these technologies would not be effective without incorporating security aspects due to a potential number of threats and attacks on the network. This paper provides a comprehensive review of the recent approaches to securing RFID and WSNs. We have carefully chosen most of these studies to investigate only the recent technique from 2017 to 2020. The paper also highlights common attacks on RFID and WSNs and the secure authentication mechanisms on these technologies. It further provides a different way of detecting varying attacks in RFID and WSNs.