But they weren't. Whether it would make a difference in the eyes of the Supremes is an entirely different question. David Weiss was a sitting United States Attorney who had been confirmed by the Senate and was serving in that role when Garland appointed him to serve in a new capacity - he was essentially retasked. Thus, he was already working for the DOJ and had been confirmed by the Senate.
Jack Smith, on the other hand, was a former US Attorney who had resigned and was no longer serving in any capacity under Garland's authority. In fact, when Garland appointed him, Smith had for several years been serving as chief prosecutor for the Kosovo Specialist Chambers in The Hague, investigating war crimes in the Kosovo War. He resigned from that position to accept that of Special Prosecutor back in the US.
So, they are far different and the argument is that Smith would need to again be confirmed to serve in a role with the DOJ, whether as a special prosecutor or any other. Again, whether the SCt. will agree with that pitch or whether it is a distinction without one remains to be seen. But, they were not done the same way.
The entire discussion though is likely moot due to yesterday's events. Both will likely be resolved through other actions. The real question is what Judge Merchan does over the next couple of weeks.