What's the Difference Between Eastern and Latin Catholic Marriage?
Do Eastern Catholics believe that the priest confers the sacrament on the couple, as opposed to the Latin Church's teaching that the couple mutually conferring the sacrament on each other with the priest acting only as a witness?
The canonical form of marriage in the Eastern Catholic Churches requires the priestly blessing for Eastern Catholics (Catechism 1623). Even if only one of the spouses is an Eastern Catholic, the priestly blessing is required for validity (CCEO 828 §§1-2).
This requirement of a priestly blessing for proper canonical form (and thus validity) is required only of Eastern Catholics. The Eastern Catholic Churches do accept as valid the marriages of Latin Catholics that were presided over by a deacon.