Discrepancy in Google Analytics reports for Audience vs. Page vs. Content Drilldown - Why?

I've been using Analytics for over a year now so I'm familiar with it though I'm haven't mastered it yet. Having said that, I need your help and guidance in regards with a discrepancy I keep running into when comparing results of a specific subfolder in a domain through the audience section vs. all pages (once it's filtered so that specific folder) and content drilldown.

I have domain www.domain.edu/ and I'm trying to get a report for January for www.domain.edu/em/ which needs to include visits, visitors, page views, unique page views, et al.

Normally I would go to Behavior > Site Content > All Pages and use the search box (under the line chart section) to filter only /em/ and so my results would like this

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So according to this report for /em/ there were 391 page views. But if I go to Behavior > Site Content > Content Drilldown the results are different

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Here now reports 387 page views, 4 less than from filtered All Pages. Okay so it's not that of a big deal and I agree... BUT if I go to Audience > Overview; results are drastic this time.

First I made sure to create a new segment and I actually used the same one which was generated when filtering for /em/ in All Pages ("Matching RegExp = /em/")

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Here now reports over a thousand page views just for January, out of the 391 page views from Page, in contrast with the 387 page views from Content Drilldown.

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I can finally see a much better complete report of what I was looking for in the first place; visits, unique visitors, etc. But the page views are way off above of what I initially was getting from the previous two reports. No wonder why my numbers were not matching when adding them up in a year (Page (from All Pages) vs. Overview)

So my obvious question is why this is happening. Am I doing something wrong in here? As far as I know, the Behavior section only contains reports designed to help you improve the content on your site to meet the needs and expectations of visitors (source) but doesn't mention anything of excluding anything.

Another question is, am I using the correct filter for the Overview section? Remember, I'm only interested on the analytics reports for /em/

Please advise. Thank you very much.