Not necessarily. Students from Asasi UiTM and Asasi UM must fill the UPU application again along with STPM, Diploma and Matriculation students, which means yes, you can apply for any degree program at other universities using your Asasi result. This applies the same when you want to further your undergraduate studies in private universities and colleges. But in this case, you have to apply directly to them considering that UPU application is only for those who want to study in public universities.
Unfortunately, the chances for you to enter IPTA through UPU application are just as same as other STPM, Diploma, and matriculation students. However, students from Asasi UiTM (and diploma students from UiTM) do receive priorities in student admission for undergraduate studies in UiTM.
Compared to KPM Matriculation, Asasi UiTM is more degree-oriented concerning that there are no prep classes, strict outing schedules, and the school kind of vibe during class. In terms of academic standards, generally speaking, Asasi has stricter exam marking. Unlike Matriculation students, they can repeat their test paper and their grade will depend on the average grade for finals (like SPM).
I am unsure of KPM Matriculation in terms of the number of students in a class but for Asasi, there are usually 30 students in a class. Enjoy the ride!