The lesser would be pictured in the old movies where the slave comes running into the kings chamber with the bad news that the enemy is marching on the city, while the delegate would be pictured by the pomp and circumstance of a finely dressed envoy entering into the kings chambers to announce good news from the far countries. And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent. Christ is just a tad more than a mear messenger or sent one, He is a delegate from God. From Vine's Word studies. There is great discussion between some of the Christian movements today as to whether there are still apostles.
Some folks believe that there are apostles today and many even call themselves apostles.
Others feel that the apostolic office is over and past - that it was an office for the transition period of the early church. These would believe that they had authority from the Lord Himself to go out and set in order the early church. There are a few in evangelical circles that believe that there is a gift of apostleship. That the early apostles were such gifted men. These usually believe that as the church grew the term and gift changed slightly and today would exist as a preacher or proclaimer of the Word.