Are they radically different understandings? No. They can have different dogma (sprinkling or immersion, for example) and radically different expressions of worship, but the fundamental spiritual truths about Christianity are all the same.
There are many denominations because not all men are reached with the same expressions. We are called to be fishers of men - if you're a fisherman, you know you use different bait for different fish and even different locations/time of day.
Many will be awed and completely captured by the ritual of High church (by that, I mean Catholicism - Latin and Orthodox, High Lutheranism, Anglicans, etc). Others will find it hollow and dry, and may be reached through Baptists, or Methodists, or another.
For example, the great awakening that John Wesley led, in the 1700s in England. All those great hymns of faith he wrote? Most of the tunes were common drinking songs! He used songs that people knew, that people related to, and added words that spoke the truth of Jesus Christ. The message is what matters, not the specifics of the delivery.
Would the truths revealed by the celebration of Mass change if the order of the liturgy changed? Say, the homily happened at the very beginning of mass?
JESUS is the way, not any institution of man! Most Protestant denominations (especially the more evangelical ones) try to model how Jesus preached and evangelized - in the common tongue, in the streets and ways of the common people. He did not stay shuttered in the temples, he did not speak only Greek or Latin. He walked among the sinners, he spoke their common language.
Remember the words of Jesus when He said "Come unto Me all who are weary and burdened, I will give you rest" (Mt 11:28). We are to come to Him, not a particular church or building or even expression of faith. The call is not to a denomination; the call is to God.
Church needs to be relevant to people so they can be made aware of Jesus. Getting a person into a church is not the end; getting a person into a church to meet God is the end! We want them to meet Jesus as He called them. However that happens is, I would submit, the absolutely correct way, the way Jesus meant it to be. And thus is "The Church".