Many introductory computer science educational platforms foster student interest and facilitate student learning through the authentic incorporation of music. Although many such platforms have demonstrated promising outcomes in student engagement across diverse student populations and learning contexts, little is known about the specific ways in which music and computer science learning are uniquely combined to support student knowledge in both domains. This study looks at two different learning platforms for computer science and music (CS-plus-music), TunePad and EarSketch, which were used by middle school students during a week-long virtual summer camp. Using both platforms, students created computational music projects, which we analyzed for characteristics of music and code complexity across multiple dimensions. Students also completed surveys before and after the workshop about their perceptions of the platforms and their own backgrounds, and we interviewed some students. The results suggest that different connections between music and computing concepts emerge, as well as different progressions through the concepts themselves, depending in part on the design affordances of the application programming interface for computer music in each platform. Coupled with prior findings about the different roles each platform may play in developing situational interest for students, these findings suggest that different CS-plus-music-learning platforms can provide complementary roles that benefit and support learning and development of student interest.