I think at the Substitution level of SAMR, a teacher is implementing either low tech options (PowerPoint, for example) or perhaps a "flashy" app or new "it" program. You're using technology for technology's sake. Although, I suppose a PowerPoint at least reaches the Augmentation level, as it can improve the delivery of information - it's organized beforehand, not all haphazardly written on a whiteboard, etc. With Substitution, it provides opportunities for teachers and students to interact less. For example, a teacher can plunk students in front of a "drill and practice" type program. Students are working alone, and the teacher isn't interacting with them either. Technology at this level has the potential to remove the social aspect from learning. However, it can also make some aspects of teaching easier and more efficient.
I think the Augmentation level has more potential to make both teaching and learning more efficient. If used correctly, technology doesn't have to remove the beneficial social aspects of learning, but it can streamline it. For example, students can collaborate on Google Docs rather than on paper. This has the potential to improve the experience of collaborating, but it does not hinder or remove the collaboration. With smart boards, chalk-talk type activities could also become more efficient. There is still the element of moving about the room, of a group sending a student to the board to share what they came up with, but the work could be saved and/or displayed more easily. The interaction and roles of students and teachers are preserved and enhanced.
I liked that in Kolb's (2017) book pointed out that there has been some confusion on whether or not the levels of SAMR are hierarchical or just "a straight line with not hierarchy and just categories" (p. 25). At the Modifcation and Redefinition levels, the lesson is said to be "transformed". To Modify means to significantly redesign the task, and to Redifine, new tasks are created that would not be conceivable without technology. I think it would be easy to use a flashy app or program and think that you are achieving this, but it definitely takes more purposeful, critical thought to execute. I think that Google Docs or other real-time, group editing programs like that could be used in this fashion. I think these levels have the potential to change the nature of the interaction between students and teachers though, perhaps removing interaction rather than adding it.
I believe learning to be an inherently social endeavor, and in my opinion, technology that enhances interaction between students (and their teacher) rather than removes it is the greatest asset.