One thing to keep in mind is also the personality of <PERSON>. He is still like <PERSON>. Thus he does not lead from the safe back but instead from the front. And his fall to the dark side also brought out more brutal tendencies than anything else...thus he is even more prone to lead from the front.
In rogue one the ship is boarded after getting disabled. <PERSON> naturally was among his men there and boaded the ship. Rushing towards the data as fast as possible when he found out where it was. Then it escaped.
As he had to reach the rebel flagship with his troops it can be assumed that they used shuttles to do so. 865
Thus he had enough time to land/board at the same time as his troops.
The next time the Tantive IV was seen was over Tatooine. Here though it was different from before. We see the corvette get disabled and docked within mere minutes. During the fight we CAN assume that <PERSON> was on the bridge and when the corvette docked he was on his way to the docking ramp (probalby first waiting to make sure not another surprise happens). As no time was to be wasted though the stormtroopers boarded the corvette as fast as possible.
So in essence.....the difference is a matter of time. In rogue one there was more time between disabling and boarding the ship so <PERSON> successfully made his way towards the enemy ship at the same time as his troops. In a new hope there was not enough time for him to get from the bridge onto the enemy ship before his troops already boarded it (and they had to board it immediately.....letting an enemy ship sit within ones hangar even disabled could get the said enemies to get wrong ideas like overloading their reactor to take the star destroyer out with them, ...).
At least that is the impression I got from watching both films (never read the novels, so not 100% if the "time difference" also comes up in them or not). 865