What did Peter tell Israel in Acts 2 and 3 about Jesus?

Peter told Israel that they had killed and murdered Jesus, but God raised Him from the dead. He proclaimed Jesus as the Christ, the Messiah of Israel, and declared that He remained in a position to be their King. This was Peter's message in Acts 2 and 3 to the nation.

Les explains that Peter, in Acts 2 and 3, told Israel they killed and murdered Jesus, but God raised Him from the dead, and He was still in a position to be their King. Peter was proclaiming that He was the Christ, the Messiah of Israel. Les connects this to Stephen in Acts 7, who likewise reviewed Israel's history and brought the leaders to Christ's crucifixion and rejection, proclaiming the same truth Peter had declared at Pentecost and in the intervening chapters. Les also notes that Saul of Tarsus opposed this message, seeing the inroads Jesus and the Twelve were making into Judaism.

Acts 2:23

Him, being delivered by the determinate counsel and foreknowledge of God, ye have taken, and by wicked hands have crucified and slain:

Acts 3:14

But ye denied the Holy One and the Just, and desired a murderer to be granted unto you;

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What is the difference between Peter's message in Acts 2 and Paul's message about Christ's death?

Peter's Acts 2 message charges his hearers with killing the Messiah, whereas Paul's message declares Christ died for you. That is a graphic difference: Peter points to human guilt in crucifying the Messiah, while Paul emphasizes Christ's sacrificial death on behalf of sinners.