What was St Paul's conversion experience and how was it life changing?

We have two biblical sources that may tell us of Paul's conversion to Christianity - Paul's own account in his epistles, and Acts of the Apostles, written at least 60 years after the event. The two accounts are overall quite contradictory, although Acts goes into some detail that is not in the epistles. Given the considerable delay before Acts was written, it is reasonable to accept Paul's account wherever the two differ in any significant way.
- Paul's account: Galatians
Paul did not say how he was converted and did not mention a vision of any sort. However, he unambiguously said that when he became a Christian he did not talk to anyone about it. In fact, he later wrote that he received his knowledge of Christianity by revelation, not from any man. He wrote of the conversion in Galations 1:15-16:
“But when it pleased God, who separated me from my mother's womb, and called me by his grace, To reveal his Son in me, that I might teach him among the heathen: I immediately conferred not with flesh and blood." †Soon after his conversion to Christianity, Paul says that he spent 3 years in Damascus, but escaped the city when the governor under Aretas, king of the Nabateans from 9 BCE to 40 CE, had a garrison deployed to arrest him because of his Christian activities. He then travelled to Arabia, then Damascus (bypassing Jerusalem), finally to Jerusalem, then Syria and Cilicia, and back to Jerusalem.

- Luke's account: Acts Acts of the Apostles describes a dramatic conversion on the road to Damascus. Either:

• Paul was blinded by a light and fell down, then heard Jesus, who told Paul that he would be told what to do when he was in the city. His men did not see the light, but heard the voice. (9:3-8) OR
  
• Paul was blinded by a light and fell down, then heard Jesus, who told Paul that he would be told what to do when he was in the city. This time, his men saw the light but, unlike Paul, were not blinded, but they did not hear the voice. (22:6-11) OR
  
• Paul saw a brilliant light but was not blinded, then heard Jesus, who gave him his mission, but did not command him to go to Damascus. He fell down, and for some reason, although there is no mention of the men seeing or hearing anything, his men also fell down.
  

In the first two narratives, the blinded Paul was taken to Damascus to be cured and taught Christianity. In the third narrative, he simply told those at Damascus and Jerusalem about his conversion experience. But his stay in Damascus was quite short, because straightaway after his sight was restored, Paul began to preach Christianity in the synagogues, until the Jews took counsel to kill him. The disciples helped him escape the wrath of the Jews by lowering him down by the city wall in a basket, and took him to Jerusalem. The governor was not involved and, in fact, would not have been at all interested in what to him was an internal squabble amongst the Jews.

- Life changing outcomes Whichever of these two (or perhaps four) accounts was correct, Paul's conversion certainly changed his life. He ceased to trouble the Christians and, instead, became a supremely successful proselytiser of the Christian faith.

According to Acts, Paul also became able to perform miracles, although Paul himself does not actually talk about them.