IMHO, if one were to lay out the EF and along side it the OF, one would see where the deletions are (e.g. prayers at the foot of the altar, the Last Gospel) were removed, and where the additions are (e.g. Psalm , OT reading).
The other main issue is the language; the EF is in Latin, the OF is in the vernacular (and yes, I know it was promulgated and can be said in Latin).
Thus, it really is not a “complete re-do” it is a series of modifications of the one rite (the EF), as per the language of SC. The structure is identical; some additions over time were deleted, and some things lost over time were put back in.