There is an equivalency being run by the GOP that is completely false on several really key points in regards to withholding aid for reasons, and more importantly how and why it is being accomplished in trying to achieve an end result.
First, that Obama withheld aid, and they got the aid from trump...
...Obama was president when the corruption was at a really bad point, and keep in mind here that the corruption stemmed very much from a stranglehold that russia had on the ukraine. Russia had it's oligarchs bleeding the ukraine in tariffs and banking, the government was being run as an arm of russia, prosecutors used the government to eliminate those who wouldn't play their game, and rewarded those who did.
...the Obama administration was in there trying to help rid them of their corrupt government, this was being done through the state department. Obama, unlike trump, had diplomats and intelligence operatives in that region that were career people who intimately knew the situation from angles that took the ukrainian view as to their independence from russia.
...Yes it was a serious concern about how aid would be used, mainly because with the degree of loyalties to russia involved at the government level, military aid could end up in russian hands used against the ukraine. Obama had been instrumental in sanctions against russia for what it had been doing in the crimea
...Where trump was concerned it was way different, there was a new president who was elected on fighting and ending the corruption and russian oligarchy influence. Oligarchs had been prosecuted, actions had been taken against the biggest bank as it was taken over, the corrupt prosecutor and many of his cohorts were removed from their positions.
...all trump had to do if he was worried about corruption being a problem would have been to work through official state department channels. The aid to the ukraine came with anti corruption strings attached. State department people could have assured him that the pentagon and state department had signed off on validating that there were no issues he needed to be worried about.
...The state department not only would have been setting trump straight on corruption, which they actually were doing, although trump had his own ideas about Ukraine e******n meddling that intelligence was trying to tell him were russian disinformation.
...Criticism and reports were being leveled at trump and his administration for withholding aid and the reasons it was being withheld, reports were being filed through proper channels that were not being followed up on.
...The OMB was also saying the block on aid was being done illegally, and trump, rather than respond to advise that congress needed to be informed, replaced the person complaining with someone who would simply sign off on the holds.
...State department and pentagon officials were getting concerned that the aid could not be provided if it ran past a fiscal deadline that was hitting the point where there wouldn't be time to fulfill the contracts necessary....which trump was fully aware of and was the actual goal
...*in documents provided by the OMB person who did testify, Mulvaney had stated that they were worried about how Putin would react to the US providing anti tank weapons. This was the real motivation for withholding military aid
Obama didn't give them missiles, but trump did...
...the record needs to be set straight on the GOP rhetorical claim that trump has done more than Obama. When the house and senate conducted hearings with the state department, intelligence, and the pentagon pertaining to the nature of national security interests involved in helping the ukraine defend itself against russian military invasions they came to the conclusion that the ukraine needed sophisticated anti tank weapons, that russian forces and tanks were being gathered at the border for an assault.
...When the house passed a spending bill for emergency military aid and it was going over to the senate, trump tried to influence the senate by saying he would not sign the bill, the senate passed it with numbers that were veto proof, and made it clear that they intended to override a veto should he try it, he chose not to take the shot to the nuts that that would have been. Trump had made it extremely clear that he did not want the Ukraine to get military aid that would be used against russian invasions.
...When the ukraine got javelin anti tank weapons, they came with a restriction that they could not be used at the border, which made no sense to say that they could not be used where they were obviously needed against russian tanks if russia attacked.
This is a long article, but does a great job of detailing the illegality and obstruction the white house and DOJ is doing to keep us from knowing what happened, and that the administration knew they were doing something that was illegal.
https://www.thedailybeast.com/trump-administration-officials-worried-halt-to-ukraine-aid-violated-spending-law?ref=home