The difference is clearly not salvation as such.
The difference is this ........
Christians are those who have been appointed by God with a special charter or mission in this age.
We have been given the task of letting others know about their salvation,
We have been given the privilege of partnering the Holy Spirit as He transforms us into the likeness of Christ, thus preparing us for our role in the coming kingdom age.
So .... we chosen or appointed ones ......... we are special, privileged people with a special, privileged assignment.
Let's not be distracted in any way, but give ourselves wholly to God's calling.
2 Timothy 2 : 4