Defrocking is the same as laicization. The idea of defrocking is to revert an ordained priest to the lay state. How this happens will be further described in this post.
Firstly, it is important to understand that in order for a priest to celebrate any sacrament, he must have both the sacramental power and canonical office. Sacramental power refers to the Holy Orders that the priest is given at his ordination. Canonical office is a recognition by the Church that this priest is permitted and tasked with the responsibility of discharging his duties as a priest. As part of having that canonical office, the priest is given faculties.
Regarding faculties
Faculties is a kind of permission that is given by the ordinary (such as a bishop) of the diocese that the priest is operating in. Ordinarily, most priests will be given faculties to celebrate the Eucharist, Baptism, Confession, Matrimony, and Anointing of the Sick within their home diocese. When operating in other jurisdictions, the ordinary of this other diocese will need to give them these faculties anew before they are allowed to celebrate these same sacraments. When lacking faculties, there are some sacraments he can celebrate validly (such as Eucharist). However, Confession and Matrimony ordinarily require faculties in order to be valid, hence unless he obtains permission, they will not be valid. Additionally, regardless of whether it is valid or not, any public celebration of the sacraments in the absence of proper faculties is considered illicit.
Regarding holy orders
According to the Augustinian or Catholic view of
Holy Orders, ordination imparts an indelible imprint upon the soul of the receiver. Hence, anybody who is ordained priest is sacramentally “a priest forever, like Melchizedek of old”. Therefore, no man can remove this indelible imprint upon the soul of the priest, regardless of what they do. Laicisation is an action performed by a man (the bishop), therefore it cannot change the sacramental power of the priest.
Laicisation/defrocking versus denial of faculties
Now, we can discuss the difference between laicisation/defrocking and denying faculties.
What
laicisation refers to is a removal of the canonical office of priest as well as all faculties of the priest. Since as I have stated above that the ordination leaves a sacramental imprint upon the priest that cannot be removed by any man, laicisation cannot change the sacramental character of the laicised priest as a priest. He still retains the Holy Orders he was given on the date of his ordination, until the day he dies. However, he no longer has the office of priesthood within the Church. In the view of the Church, he has become a layman and lost all faculties to celebrate the sacraments, and is to all intents and purposes treated like a layperson, except in certain circumstances
in extremis which are specified in Canon Law.
Denial of faculties, on the other, is a more vague term. Strictly speaking, it simply means that the priest has lost the permission to celebrate any number of sacraments, whether or not he still retains the canonical office of priest. Usually, what happens in that a travelling priest enters a diocese, but the reigning bishop prevents him from celebrating any sacrament validly. He still remains a priest, but is not allowed to perform the public work of a priest within that diocese.
An example is Fr. Helmut Schüller, an infamously heterodox priest. While travelling the USA to promote his anti-Catholic “Appeal to Disobedience” cause, he was denied faculties by the Archdiocese of Philadelphia. Therefore, he is not permitted to celebrate anything in the Archdiocese of Philadelphia unless there is a dying Catholic penitent who requires a confession, or a dying non-Christian who requires a baptism. Furthermore, he is not able to do anything else a priest is usually empowered to do, such as giving homilies or public speeches within Church properties. However, Fr. Schüller still remains fully a priest within the Archdiocese of Vienna with full faculties to celebrate the sacraments as a priest in Vienna, and is therefore still a priest in the eyes of the Church, even though he may not have permission to discharge his powers as a priest in the Archdiocese of Philadelphia (or other places where he is denied faculties). Many Catholics have been clamouring for his laicisation. If he were to be laicised, then he would be no longer considered a priest, we would no longer address him as “Father”, and he would no longer have faculties to celebrate anything anywhere. He may celebrate the Eucharist validly, but it would be illicit. However, in his lay state, he would still be permitted (and in fact compelled) by Canon Law to hear the confession of a dying penitent and baptise a dying non-Christian.
I hope this helps and wasn’t too long-winded.
IOW, I liked it. 
