Smart cities are becoming more reliant on interconnected systems for the purpose of monitoring and managing operations in real time. As a result, the security of the networks is paramount. This research examines the security vulnerabilities and resilience of ZigBee and LoRaWAN, the two most widely used Smart City network protocols, through a series of three experimental approaches: sniffing ZigBee, sniffing LoRaWAN, and comparing the effects of signal jamming against both Zigbee and LoRaWAN networks. We used the RF transmitter ZigBee, which is commonly deployed in smart city infrastructures to conduct the experiment. The results of the experiment and our analysis show that there are some potential attack vectors on the Zigbee network even when operating with 128-bit AES encryption. In the second experiment, we looked at the security of the LoRaWAN network which is commonly used in utility management and environmental monitoring applications. The results of the study demonstrated the possibility of sniffing LoRaWAN uplink and downlink packets. We used an Arduino Uno WIFI Rev 2, a Dragino LoRa shield, and an Adafruit Feather 32u4 board in setting up a malicious gateway, which revealed significant insights into the security mechanisms and vulnerabilities of LoRaWAN. The third experiment compared the resilience of LoRaWAN and ZigBee with signal jamming attacks using Hack RF One. This research was conducted in a controlled environment, which proved that LoRaWAN has superior resilience; even in the presence of a jamming signal, it continues to receive data while ZigBee stops functioning. This will benefit intelligent city planners and IoT device manufacturers in selecting robust and secure wireless networks.