Here my friend is both a short answer and a more detailed reply. THANKS for asking
Catholics hold and always have that Salvation is a PROCESS not a single step.
The Process is centered around the Seven Sacraments
Baptism
Eucharist
Confirmation
Penance [Confession of our sins John 20:19-23]
Marriage
Holy Orders [the priesthood extended from the time of Moses; now perfected
The Last rites
Each of which was Instituted By Christ either explicitly or implicitly Mt 16:015-19
Protestants hold very often to Once Saved Always Saved; Altar calls and the Sinners Prayer; none of which is biblically grounded when using the entire Bible.
Part of the difference is our different views of the necessity of Suffering.
Non-catholic s often take the position that Christ DID IT ALL, which is not biblical when using the entire New Testament.
Because GOD suffered so much for us Christ Himself TAUGHT that we too must expect to suffer in order to prove our love for Him.
Take Up your Cross and Follow Me
Phil.2: 8 “And being found in human form he humbled himself and became obedient unto death, even death on a cross Luke.9 :23 And he said to all, "If any man would come after me, let him deny himself and take up his cross daily and follow me.Mark.8: 34 And he called to him the multitude with his disciples, and said to them, "If any man would come after me, let him deny himself and take up his cross and follow me. Luke.9: 23 And he said to all, "If any man would come after me, let him deny himself and take up his cross daily and follow me. Luke.14: 7 Whoever does not bear his own cross and come after me, cannot be my disciple.” Matt.5: 19 “Whoever then relaxes one of the least of these commandments and teaches men so, shall be called least in the kingdom of heaven; but he who does them and teaches them shall be called great in the kingdom of heaven. “ Matt.19: 17 “And he said to him, “Why do you ask me about what is good? One there is who is good. If you would enter life, keep the commandments.”
Your question requires much further discussion but space is limited.
God Bless you!
Patrick