Master's Program at Harvard Extension School

[Zachcleigh]

One thing I would point of with these degrees is that they are in extension services.  
For example: The HES Masters of Science in Data Science Degree is actually displayed as an ALM in Extension Services (Field: Data Science)

This is what has turned me away from considering this option personally.

Diplomas read "extension studies", not "extension services". There are no MS degrees awarded by HES. It's basically a bit of academic arcanum, kind of like how a PhD could be in any field. Within the school itself students and staff (most of whom are not degree seekers), apply common sense when discussing their concentration and degree name. (nobody would ever describe the HES Data Science program as a MS in Data Science, because it would be inaccurate to say so, and SEAS actually has a completely unrelated full-time MS Data Science program)

You are correct. Extension Studies* I was typing a bit too fast on my end. 
Harvard does have a separate and unrelated MS in Data Science degree like you’ve said. Personally if I’m going to do the work for an MS in data science, I would want that degree. However, not everyone shares the same opinion and I will admit that Harvard degrees (whether HES or not) come with a level of clout for the resume.