As some have pointed out, Russian collusion and Ukraine corruption are inter-related affairs in many ways:
1) both involved Trump's willingness to have foreign countries interfere in US presidential elections
(Trump publicly asked Russia to hack Clinton, he benefited from Putin/wikileaks hackings, he denies Russia interfered and claims Ukraine interfered in the last election despite all intel, and he tried to get Ukraine to interfere in this cycle by sliming the Bidens, plus asking China to investigate the Bidens)
2) both benefited Putin and Russia
3) both involved multiple instances and levels of obstruction of justice. (Mueller shouldn't have let Trump brazen things out and not testify. And shouldn't have pretended a president can't be charged with crimes).
4) Trump had a secret tower project under negotiation in Russia, while Giuliani has all sorts of sordid business deals in Ukraine. Meaning Trump and his lawyer were both hiding stuff foreign countries knew about, and were seeking to profit on their relationships with foreign gov'ts.
Even if these are separate events, they provide a distinct MO. But there seems a fair amount of entanglement. A willingness to solicit foreign interference in US elections, beholden to foreign powers who know your secrets, obstructing legal probes into the matters, and at the heart of it all an unnerving subservience to Putin and his best interest.