Luther's greatest contribution to the Reformation was his reaffirmation of the principle of justification by faith alone through grace. That was the pillar of God's Word upon which he stood, and that was the major battle that he fought (he fought others as well).

As to worship, he viewed the fundamental problem with Roman rites as being obligatory and required to please God rather than adiaphora, as he saw it. He thought that ceremonies and rituals might have a place in worship as long as they were not forced upon the conscience or tied to our righteous standing before God.

Calvin understood the nature of true worship much better than Luther. He saw that right worship at its core must involve apprehension of God as he is revealed to us in the word by faith and according to the manner which God has ordained for us to approach him. Anything else is presumption on our part.

Comparing the two, I would simply say that Calvin was more consistent than Luther in applying the principle of sola scriptura to worship. True religion is neither adding to nor taking away from God's Word. The traditions of men in worship always supplant God's word and therefore make such religion vain will-worship.

There is further helpful explanation of Lutheran inconsistencies in the area of worship to be found here.

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Andrew