They did separate them. Same reasons the Trump administration is doing so...but the Obama administration realized there's be an outcry over it, and backed off to trusting "the honor system." Which is what Trump labelled "catch and release" during the campaign.
The difference is basically that the applicable laws aren't "nice," and the Obama policy was to "be nice" and ignore the law, while the Trump policy is to enforce the law to show how flawed they are and encourage Congress to amend them.
The *****? "It's true...but Trump still lied."