This is John 6.
What he told the unbelieving crowd was essentially a parable.
What he told the disciples was the unvarnished truth.
So He explained to the unbelieving crowd something they didn't get and after telling them to eat His flesh and drink His blood, they turned away instead of seeking the real truth.
What He told the disciples who stayed around for the real truth, it that.....
John 6:63 It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life.
So He was in effect saying that it ISN'T eating flesh that makes the difference. He Himself said it was no help at all. Therefore it CANNOT give life because, He goes on to say, it's the SPIRIT who gives life, not eating bread or flesh or any other such thing.
What is important to stress here is that the hearers who thought that Jesus meant that He wanted other humans to literally eat His flesh and to literally His blood, they rejected that concept in that it was nauseating to them and contrary to Biblical ordinances, and ceased to be taught by Him.
On the other hand, those who remained where the ones who by His training and personal guidance discerned that His words were aimed inviting others to come to Him in fellowship and to commit trust in His teaching. They where the ones that knew that no one else could quench their yearning for spiritual nourishment, and in their time with Him never had to actually ingest any part of His material body. What they wanted was union with His Spirit, to imbibe His absolute everlasting life and unfailing counsel.
And that is what they received, without any voodoo about transubstantiation, on the morning of one unique Pentecostal gathering. And so have we who have experienced and know the gift new life, of His indwelling Spirit, and His endless Love