Why was Copernicus not persecuted by the church, but Galileo was?

Galileo lived under the rule of the church in Italy, and counted himself as a devout Catholic. Copernicus lived in Prussia/Poland, whose government did not have direct ties to the Catholic church, and it was a region where the Lutheran/Protestant church was prominent.

The Catholic church did not press charges against Copernicus, because they were not in a position to do so.

You can read the condemnation of Copernicus' theories yourself on the following link.

I am sure others might have a better answer, but from my knowledge, there were three big centers of inquisitions in Europe:

• Spanish Inquisition
• Portuguese Inquisition
• Roman Inquisition

The Roman Inquisition had it's influence on Polish Kingdom, but for most of Copernicus' life Sigismund I of Poland was the king of Poland who was famous of supporting Renessaince, art and science. Poland in that time was a very potent and influental country in Europe, so my best guess is that Roman Inquistion couldn't do much more than just condemn Copernicus' theories, unlike Galileo who worked in various parts of Italy where the Inqusition had greater impact.

In 1559, Copernicus's De Revolutionibus was placed on the Index of Forbidden Books (source).

Before Copernicus, Bishop Nicole Oresme (d. 1382) advanced the hypothesis that the earth, not the heavens, rotates diurnally. He was not condemned because he did not reinterpret Holy Scripture to support his scientific view.

Galileo was condemned because he ventured into Scriptural exegesis—in, e.g., his 1615 Letter to the Grand Duchess Madame Christina Lorraine—contrary to the unanimous consent of the Fathers of the Church and the Council of Trent. Copernicus did not do Scriptural exegesis regarding heliocentrism.

Galileo was condemned as "vehemently suspected of heresy" for holding "The proposition that the Sun is the center of the world and does not move from its place[, which] is absurd and false philosophically and formally heretical, because it is expressly contrary to Holy Scripture." (1633 Condemnation).

To say Galileo was persecuted seems to imply he adhered to a different religion than Catholicism. He was a devout Catholic,* hence the Church had jurisdiction over him in moral or religious matters. His house arrest was quite unusual; it was really a paid retirement, during which he wrote his most important physics work, The Two New Sciences (1638).

As the Tuscan ambassador Francesco Niccolini wrote on 27 February 1633 (p. 225 of Maurice A. Finocchiaro's The Galileo Affair: A Documentary History):

His Holiness [Pope Urban VIII] answered that he had done Mr. Galilei a singular favor, not done to others, by allowing him to stay in this house [the Tuscan embassy] rather than at the Holy Office, and that this kind procedure had been used only because he is a dear employee of the Most Serene Patron [the Pope] and because of the regard due to His Highness [the Pope]; for a Knight of the House of Gonzaga, son of Ferdinando, had been not only placed in a litter and escorted to Rome under guard but was taken to the Castle and kept there for a long time til the end of the trial. I showed myself to be aware of the nature of the favor, and I humbly thanked His Holiness [the Pope];

and on 16 April 1633 (p. 250-51 of ibid.):

Indeed, there is no precedent of anyone ever having been interrogated during a trial without being detained in a prison cell, and in this regard he has profited from being employed by His Highness [Pope Urban VIII] and from being lodged at this house; nor is there knowledge of anyone else (whether bishop, prelate, or nobleman) who, immediately upon his arrival in Rome, has not been kept at the Castle or at the same palace of the Inquisition, subject to all rigor and strictness. Furthermore, they even allow his servant to wait on him, to sleep there, and, what is more, to come and go as he pleases, and they allow my own servants to bring him food to his room from here and to return to my house morning and evening.

This singular treatment can hardly be considered a persecution.

His house arrest began at the same Tuscan embassy on 24 June 1633. On 1 December 1633, the Pope allowed Galileo to return to his villa in Arcetri, near Florence, where he stayed for the rest of his life.

1. solemn recantation on 22 June 1633—in which, according to this, he omitted saying he was a bad Catholic, which the version presented to him by the cardinals had said.

2. letter to Francesco Rinuccini, Arcetri, 29 March 1641, the year before his death (translation from Le opere di Galileo Galilei, vol. 7, p. 361, ed. by Vincenzio Viviani):

   The falsity of the Copernican system needs not be called into doubt, and especially by us Catholics, having the irrefragable authority of Sacred Scripture, interpreted by the supreme masters in Theology, whose concordant consensus renders us certain of the stability of the Earth placed in the center, and of the mobility of the Sun around it. The conjectures then for which Copernicus and his other followers have professed the contrary, are all lifted with that most solid argument of the Omnipotence of God, Who can do in diverse—rather, in infinite ways—that to our opinion and observation seem done in one particular way; we should not want to shorten the hand of God and tenaciously sustain that in which we can be deceived.