Paul may have upset but never disagreed besides it was Paul who was the scholar when it came to scripture. and it wouldn't take much for Paul to upset seeing sometime before he was persecuting their brothers in Christ. ruffling a few feathers is a natural occurrence with any group, so what, again, that's not proof there was discrepancies in doctrine.
I take it after you have reviewed Acts 15 and 21? Let me make some points:
1. In Acts 1519-20 James delivers his sentence, which is not to trouble the gentiles with the law (especially circumcision, but in reality, the whole law.
2. Nowhere does James free Jewish Christians from the Law. This will become a big problem and will be shown to be true later.
3. Paul never agreed. I say that because there is no indication that he ever preached all those 4 points. The ones he did, he was already preaching. Later in Galatians he said they seemed to be pillars, but they added nothing to him. This is NOT a compliment.
4. To say there wasn't a difference in doctrine while there was a council to debate doctrine is a contradiction.
Next, lets review Acts 21:
1. Lest anyone think I believe they were enemies, I acknowledge 21:17-20.5. Paul is received with joy.
2. In verse 20-22 James mentions a big problem: appearently Paul had been teaching that Jewish Christians weren't under the Law either. That they should forsake Moses. Mind you, these were believers (Christians) who were still zealous for the Law and Paul was teaching differently.
3. Verse 25 is where James reminds Paul that he excused the gentiles, but if you had any doubt that James didn't excuse Jewish Christians in Acts 15, this chapter is absolute proof otherwise.
4. The fallout is that Paul and 4 others must perform a ritual to purify themselves and James says it will show that Paul himself-- a Jew, of the stock of Benjamin-- was willing to keep the law! Thats in verse 24. James was asking Paul to go against his own preaching!
5. Those are all facts. They are undeniable unless you can show me I missed something. Its happened before, so let me know if I did. Now, THIS is my opinion: I have no idea why he agreed to do it! I certainly don't believe he thought it was necessary nor do I believe he thought he was wrong. 1 Cor 9:20 is the only possible explanation. Now I submit myself to Paul as he was the Apostle and I will not say he was wrong. I am just saying I dont fully comprehend his decision.
Let me ask some concluding questions:
1. Before the Jerusalem Council, did James believe that all Christians should keep the Law while Paul did not?
2. During their meeting in Acts 21 did James believe that Jewish Christians should still keep the Law (Including Paul himself) while Paul did not?
3. While Paul preaches against fornication and was against idols, do you ever see him strictly enforce the rules James set forth for the gentiles?
The answers to these questions is yes, yes and no. So the final question:
4. Was there a difference in doctrine between the two when one believes that Jewish Christians are still under the law, and that the gentiles have some rules in place, while the other does not?
I'm going to ask a question for reflection... No need to answer. They are for anyone looking at this thread: do you believe that Jewish Christians still must follow the law? Because that is what James was teaching and that is what Paul taught against.