Students' perceptions towards synchronous and asynchronous online delivery modes of three engineering courses, in a large UK university is conceptualised, inspired by the Community of Inquiry theoretical framework. Using a qualitative methodology, 76 written student narratives were analysed. An overwhelming focus on the elements that helped them to process the information being taught and to synthesise their understanding (cognitive presence) was found, regardless of the delivery mode. Furthermore, despite the perceived benefits in terms of time management, narratives of asynchronous learning lacked connectivity between such cognitive elements and those allowing them to interact, share, and communicate their understanding with their peers and teachers (social presence). Student reflections on which delivery mode best supported their learning were conflicting at times, but a balance between cognitive and social presence is recommended to integrate the opportunities that stem from both.