DACA was announced in June 2012. At the time, there were no meaningful legal challenges to the policy. Indeed, as hundreds of thousands of people received benefits under the policy, it became clear that the courts would not let it be halted.
DAPA was very different. By late 2014, the Republican Attorney General Machine was operating at full steam. Attorney General Abbott challenged the policy in the U.S. District Court for the Southern District of Texas, Brownsville Division. The brainpower on that case was staggering. Among others involved were Andy Oldham (5th Circuit), Jimmy Blacklock (Supreme Court of Texas), Brantley Starr (NDTX), Cam Barker (EDTX), Scott Keller, and more that I'm forgetting. This case innovated the "Driver's License" theory of standing, which has formed the basis of countless challenges to immigration non-enforcement. I filed an amicus brief back on behalf of the Cato Institute. (No, Cato would not file such a brief today.)
The DAPA challenge was successful, in large part, because a preliminary injunction was obtained before anyone was able to sign up for it. DACA, by contrast is still on the books. Even after President Trump tried to rescind DACA, Chief Justice Roberts made up some convoluted test about reliance interests to ensure people could keep their deferred action and work authorization.
