So would charging Trump with obstruction let Garland off the hook on the Clinton comparisons?

Obstruction might be an even more hypocritical charge to make 

We need to remind people that:

• Clinton declared 33,000 emails to be "personal" and deleted them using "bleachbit" while her laptops and emails were under federal subpoena.
• FBI later found 49,000 emails from a laptop shared by Clinton aide Huma Abedin and Anthony Weiner long after Clinton legal team had said all laptops and emails had been turned over. There was previously unknown classified information found there as well. 
• Many of the emails found on the Abedin Weiner laptop were sent to or received from Clinton, but were not part of the emails Clinton provided. Proving that Clinton deleted government emails (apparently some with classified information) along with personal.  

Let's start with the concept that anything on Clinton's work server (even if she created herself) is the property of the US Government just as much as anything the President works on is property of the US Government. Everything on that server would technically have been required to be made available under the FOIA - which is exactly the same reasoning for the 1978 PSA and the National Archives.  Where there is a difference, that difference favors a President over other members of a cabinet. Presidents are provided the idea of privilege and such that cabinet members do not enjoy.

In other words, Clinton had no more authority to declare emails personal and delete them as Trump would have to declare documents at Mar-a-Lago personal and have them burned. Would have been the exact same thing under the law. Does anyone believe that Trump could have gotten away with such an act? 

So what we have is clear evidence (and no denial) that Hillary Clinton destroyed/deleted information that was not only subject to the FOIA, but also under congressional and Federal subpoena, Yet there is no evidence that Trump destroyed anything. At best, they might argue that documents had been in his office rather than in the storage facility.  Either because they were moved or because they had always been in that office. The same office, of course, that had been declared a secured briefing room. 

Meanwhile, the idea that 100 documents with classified markings were found after a letter was written saying there was no classified documents still gets into the murky argument about whether or not the President declassified them. But there was no murkiness regarding the 49,000 work related emails on the Abedin Weiner laptop. Those emails were relevant to the investigation, should have been turned over, and most importantly proved that Clinton deleted work related emails in her 33,000 bleachbit purge.

Bottom line; the DOJ has no case against Trump on mishandling sensitive documents if they apply the Comey/Clinton standard. That is so obvious to everyone that the DOJ appears to have given up on even trying to go down that road. 

But the idea of obstruction (when you compare the two situations) will likely be a much worse comparison. Clinton obviously was far more and far more blatantly obstructive while she was under investigation. She destroyed subpoenaed information. She was caught lying about it.  Why wasn't she charged? 

Trump may not have been as cooperative with the Archives as he otherwise should have been. But there is no evidence that he destroyed anything (as Clinton did) and he has allowed access to the FBI previously to the location that they raided (whereas Clinton resisted turning over her laptop even after it was subpoenaed). Perhaps at some time the FBI needs to take responsibility for not finding the documents that they apparently were sure all along were at the storage facility the first time there were there. 

Maybe Garland has something more. Some real evidence of a nefarious plot to sell this information to the Russians or something.

Short of that, they have way less than the FBI had on Clinton in 2016.