It occurs to me that some of the major differences between Newman and Manning’s later careers can already be glimpsed in their early lives. Specifically, in the reasons they converted.
Cardinal Manning converted after Newman when, in 1850, the Privy Council forced the Church of England to ordain an Evangelical who denied the salvific efficacy of Baptism. This move so shocked Manning that he immediately saw that the Church of England was essentially a political construct without any share of the Apostolic inheritance. It could not resist the demands of the state. And thus, he betook himself to Rome.
Newman became a great theologian; Manning became a great ecclesiastical politician. Newman suffered many troubles with controversies and the censure of the authorities; Manning labored as part of the Catholic establishment and did more than anyone else in England (and, due to his role at Vatican I, arguably the world) to advance the cause of Ultramontanism.
On an unrelated note, there is a rather amusing point of contrast in their biographies. Newman matriculated as an undergraduate at Trinity College, Oxford. Manning was at Balliol (like Faber). Anyone who’s been to Oxford will know that these two colleges are next to each other on Broad Street.