The Cross is apostolic and universal; Corpus Christi is a thirteenth-century Latin institution answering a thirteenth-century Latin controversy. Age and reach both favour the Cross.
Widest gap in the scope. One is the event the faith stands or falls on; the other is a devotional feast of the mode of presence at that event's memorial.
A universal feast attested in every ancient calendar against a dated Latin institution.
The death itself against a feast of the mode of its memorial.
Neither is scripturally dated, but one is ancient and universal tradition and the other has a papal bull with a date on it.
Even a feast of pure doctrine outranks a feast of a devotional practice, since the doctrine is the reason the practice exists.