The current research aimed to develop & compare between two different learning mobile websites designs, which are responsive versus adaptive. The best design amongst them is determined in terms of learners' preferences. To conduct this, the researcher formulated a preference level test (PLT) and installed it on both websites. 84 undergraduate students participated in the main experiment. They were divided into two experimental groups; each group consisted of 42 students. The first group used the responsive website (RW), while the second group used the adaptive website (AW). The results showed the superiority of the second group in the PLT with a statistically significant difference. The research recommended the necessity of raising awareness about the importance of mobile learning, as well as the adoption of effective designs, which enhancing the students' level of preference.