Well, Bruno is his team's defacto setpieces player hence he was bound to have better stats.
First, both don't dictate play in what I've seen from their YouTube compilation, hence they are no midfielders but attackers.
However while watching their clips, I noticed Felix being mostly manmarked whereas Bruno wasn't. I don't know the reason for that, considering they play in the same league. It could be that opposition teams saw a chance of getting maximum 3 points against Sporting Lisbon hence didn't bother man marking anyone whereas they couldn't afford to do same to Benfica. The few times I saw Bruno being manmarked in the clip, the play was discontinued which means, he couldn't found a way through whereas Felix did multiple times, either through his quick speed of thought, technique or vision. All I see is Bruno dropping back into open space to punt long ball forward or takes long shot. There are few times he runs into the box to finish up his team's move and that's it.
I don't see what he's got to offer us in the midfield with that kind of style whereas I could see Felix operating as a striker for us because he's got everything to be a striker. Apart from his movement and positioning, he's an aerial threat and has got the presence. In fact, in the match he played as a striker against Frankfurt, I would say Frankfurt got back into the game after Seferovic came on and Felix was dropped back into the SS role but while he was deployed as the only striker, Frankfurt couldn't deal with his presence, movement and linkup play. He was a terror throughout until the coach moved him further back later on.