John uses agapao to express a different idea than when he uses phileo. Both are verbs that mean to love another. Phileo comes from an adjective (G5384) and has the meaning of loving someone as a family member, i.e. brotherly love. Families share everything, so the nuanced meaning is to be kindly toward another and share with them what you have. So rather than exercising the sloppy eisegesis of claiming there was no intended difference in meaning, let’s let the word usage speak for itself.
Lets look at a few verses from John where he uses phileo rather than agapao.
John 5:20, For the Father loves the Son, and shows Him all things that He Himself is doing; and the Father will show Him greater works than these, so that you will marvel.
If we use the more specific meaning, the verse could be translated as “For the Father loves the Son as family, and shows Him everything He does; and the Father will show Him even greater works than these, so that you will marvel.
John 11:3, So the sisters sent word to Him, saying, “Lord, behold, he whom You love is sick.
Here in the view of the sisters, Jesus loved his close associates as members of his family, thus ... he whom You love as family is sick. Now we will learn at the end of this gospel that Jesus also displayed agapao love by laying down His life for His present and future "family" that includes Lazarus.
John 11:36, So the Jews were saying, “See how He loved him!
In the view of those seeing Jesus weep, they understood that Jesus loved Lazarus as family. And they were right! Too bad the translation to not present the full message of God, i.e. "See how Jesus loved him as family."
John 12:25, He who loves his life loses it, and he who hates his life in this world will keep it to life eternal.
Contextually, he who has a loving relationship with his or her life in the world will destroy it, but he who hates his life in this world will keep it to life eternal. The idea is not that we should not love ourselves, i.e. love your neighbor as yourself, but a loving relationship with the world makes us enemies of God. Here, I think the best that can be done, is to footnote “loves his life” with “or has an affectionate relationship with his worldly life.”
John 15:19, If you were of the world, the world would love its own; but because you are not of the world, but I chose you out of the world, because of this the world hates you.
Same usage of “phileo” referring to a relationship (friendship) between the elect and the world. A better translation choice would be “…the world would love as family its own….”
John 16:27, for the Father Himself loves you, because you have loved Me and have believed that I came forth from the Father.
Here, the Father loves you as family because (1) we have loved Jesus as family, and (2) we believed that Jesus is the Christ sent from God.
John 20:2, So she ran and came to Simon Peter and to the other disciple whom Jesus loved, and said to them, “They have taken away the Lord out of the tomb, and we do not know where they have laid Him.”
Here we have Mary’s perspective, Jesus loved as family the other disciple, which is not to say Jesus did not also love John to the greatest extent, i.e. He died for John and all mankind. The claim of interchangeability rest on the idea both words mean the same thing, rather than Jesus loves others in two different ways, as family and as someone He would die for.
John 21:15, So when they had finished breakfast, Jesus said to Simon Peter, “Simon, son of John, do you love (agapao) Me more than these?” He said to Him, “Yes, Lord; You know that I love (phileo) You.” He said to him, “Tend My lambs.”
Here, some mistakenly claim John is using the words interchangeably, but nothing could be further from the truth. Peter loves Jesus as a brother, but is not prepared to die for Jesus. And that distinction is essential to the message of God.
John 21:16, He said to him again a second time, “Simon, son of John, do you love (agapao) Me?” He said to Him, “Yes, Lord; You know that I love (phileo) You.” He said to him, “Shepherd My sheep.”
Peter is still not prepared to die for Jesus. And Peter is distraught; because He does not think his all too human love is enough for his Lord and Master.
And now we come to one of the most powerful and compassionate verses in all scripture, and one which some seek to obscure.
John 21:17, He said to him the third time, “Simon, son of John, do you love (phileo) Me?” Peter was grieved because He said to him the third time, “Do you love (phileo) Me?” And he said to Him, “Lord, You know all things; You know that I love (phileo) You.” Jesus said to him, “Tend My sheep.
Rather than asking Peter if he loves Jesus with the agapeo, willing to die for love, Jesus asks if Peter loves Jesus as a brother! But note that this human love, imperfect and falling short of our goal, was acceptable to God. Jesus will accept us where we are, warts and all.
Finally, let’s consider why Peter said that Jesus had said to him a third time, “Do you love (phileo) me, when this is actually the first time Jesus had used that word. Since agapao is a general term for love, and therefore has shades of meaning that overlap with phileo, it appears Peter did not immediately grasp any significant difference in Christ’s question. Jesus realizes this oversight by Peter, and thus explains it to him in verse 18. Peter will grow in his devotion to Jesus, and one day will die for Jesus.
So while it seems a fad to claim interchangeability, the evidence stacks up highest on the other side. John uses agapeo as a commitment, a willing to die for kind of love, but uses phileo as an affectionate love as if toward a friend or family member.