Did Obama order Democrats to get dirt on Trump from Ukraine?
Asking a foreign government to cooperate with an investigation of credible allegations of corruption with real evidence (even a video recording of an admission!) is legitimate, even if the suspect is running for the nomination to oppose you. You don't get a pass from corruption laws because you run for office -- or rather, you shouldn't, even though it seems to work that way for Democrats. Thatg's what Trump has been doing: asking for cooperation with legitimate investigations.
Giuliani seems to be saying Obama actually ordered Democrats to dig up "dirt" on an opposition candidate.
If true, there's a substantial difference between the two. A legitimate investigation versus a political hit job.
Now, we don't know yet what Giuliani is describing. We'll have to evaluate that when we see the evidence. But we do know what Biden admitted to doing -- conditioning US aid on firing a prosecutor investigating the company his son worked for. That seems corrupt on its face.
Mind you, we know a little about what came out of Ukraine in 2016 about Trump. This was the "black ledger" allegations against Manafort. There is speculation they might be straight up fakes. If that's what Obama ordered and what Ukraine delivered, it's election interference by fraud and abuse of office.
Obama has shown no reluctance to interfere in foreign elections himself, so it wouldn't be surprising to see him soliciting interference to help his party at home.