I'd argue that isn't quite the same thing.

For starters, OAM doesn't confer the title of "Sir" or "Dame" for some reason despite the award still coming from the Monarch of Australia (i.e. the Monarch of the United Kingdom). It seems to me that this was a deliberate choice to not to "dilute" the title when they created the award, suggesting OAM doesn't carry quite the same intended prestige as OBE.

Secondly, Brady Haran's tenure on YouTube is 6 years longer than Tom's (2008 vs 2014), if we're talking about regularly posting videos vs just uploading random projects, and Brady's videos directly promote higher education and academic research through his collaboration with the University of Nottingham. He also worked for the BBC as a journalist for six years before that. This isn't to diminish Tom's work, but I think objectively speaking he's not quite as prolific.

Thirdly, I believe Australian citizens can still receive OBEs as citizens of a Commonwealth realm, so Brady may still receive one down the road, especially if he sticks with it. But if he hasn't gotten one yet, I doubt that Tom would at this point in time.