Manti had incredible anticipation and play-reading, particularly in his final year where he was really dialled in to what the opposition was looking to do, so he was very good against the pass. Jaylon is explosive closing the distance to the ball-carrier and a violent tackler so he is very good against the run.
In years-gone-by though, a linebacker built like Manti would have bulked out and been a downhill run stuffer, and a backer built like Jaylon stayed lean and wiry and would have been a finesse pass-cover and pass-rusher on the edge.
They are both unique in the crossover of their skill-sets but fundamentally different creatures as linebacker. Different assignments, different roles.