They are equal, but they are not identical. In God's wise and mysterious economy, each divine person of the Trinity, in full cooperation with the other persons, contributes uniquely to God's great and gracious works of creation, salvation and sanctification. To be sure, the fall has also corrupted the relationship between man and woman as originally designed by God, so that what was intended by God as a blessing is often misunderstood and abused by both women and men. The oneness of male and female in Christ affirmed by St. Paul in Galatians 3 does not nullify the distinction between them given by God in creation, but rather sets both men and women free to relate to each other in accordance with God's original will and plan. All of the redeemed are equal before our gracious God, but each retains his or her unique and God-given identity and is called to respond to God's grace in Christ in ways that, according to Scripture, are commensurate with that identity.
Subordination is for the sake of orderliness and unity.
St. Paul goes on in Ephesians 5 to speak specifically to wives and husbands about marriage as reflecting, in a real and mysterious way, Christ's relationship with His church. For the husband is the head of the wife as Christ is the head of the church, his body, and is himself its Savior. As the church is subject to Christ, so let wives also be subject in everything to their husbands. Husbands, love your wives, as Christ loved the church and gave himself up for her . . . The submission of the wife is rooted in and exemplified by the church's submission to Christ, which is a willing, joyful and grateful response to the bridegroom's undeserved and inestimable love.