If look at the two, they do have almost the same equality in terms of strength performance, but each has advantages that cannot be differentiated.
Brighton is in the Premier League competition with 7th place in the standings and they are used to facing several big, quite strong team such as Manchester City, Arsenal and also Liverpool who are currently in very good condition.
In contrast to Roma, which in the Serie A competition occupies 6th position in the standings and perhaps only faces strong team such as Inter Milan and Juventus, this difference will create an advantage in terms of ease when the two teams compete.
In the first leg, Roma will have home game and this is clearly an opportunity for them to win and have an aggregate advantage, but I sure Brighton will not give up and let Roma win.
Brighton must at least be able to maintain draw and try to win the match in the second leg when the home game is theirs, but I will also have little difficulty in determining who will make it through to the next round.
They each have advantages and disadvantages, perhaps predictions can really be made with more certainty when the first leg match is finished.
I don't agree that both have almost the same performance because as far as I know, each club have different performance depending on whether they have quality players or not. Brighton is in a quite difficult league as you said. Brighton is used to facing quite difficult clubs as you mentioned and the competition in the Premier League is very tight and not as tight as the Italian league. Even though both of them are almost in the same rank, Brighton's achievement in 7th place is not an easy thing to overcome, therefore we cannot view both of them as having almost equal performance because in fact they do not have the same performance, but if we look at it from the perspective of Roma's experience has better experience in the Europa League than Brighton, therefore it is natural that Roma is still superior in this match.
Just like you, it is also difficult for me to predict between the two clubs who will qualify for the next round because to be honest I doubt Roma because currently they are no longer coached by Jose Mourinho who has better experience than De Rossi but yes, we also don't know De Rossi abilities yet in all, but if you look at the play off round, Roma seems to a little difficulty against Feyenoord, even though as we know last season, Roma was able to beat Feyenoord in the first leg and second leg in the European league, but this season Roma was only able to draw in two meetings, if not because of the penalty, it is possible that Roma will not qualify for the round of 16 Roma was quite lucky in that match.