Judas planned his betrayal of Jesus. Matthew 26:14-16 (NKJV), 14 “Then one of the twelve, called Judas Iscariot, went to the chief priests 15 and said, ‘What are you willing to give me if I deliver Him to you?’ And they counted out to him thirty pieces of silver. 16 So from that time he sought opportunity to betray Him.”
The Gospel of Luke adds that Satan entered Judas. Luke 22:1-6 (NKJV), 1 “Now the Feast of Unleavened Bread drew near, which is called Passover. 2 And the chief priests and the scribes sought how they might kill Him, for they feared the people. 3 Then Satan entered Judas, surnamed Iscariot, who was numbered among the twelve. 4 So he went his way and conferred with the chief priests and captains, how he might betray Him to them. 5 And they were glad, and agreed to give him money. 6 So he promised and sought opportunity to betray Him to them in the absence of the multitude.”
At the Last Supper, Jesus announced that one of the disciples would betray Him. Those at the table asked who would be the betrayer. Judas knew what he was about to do, but he pretended to be a loyal disciple. Matthew 26:25 (NKJV), “Then Judas, who was betraying Him, answered and said, ‘Rabbi, is it I?’ He (Jesus) said to him, ‘You have said it.’ ”
Judas betrayed Jesus with a lying kiss. Betrayal is very painful; however, Judas used a kiss to inflict even more pain. Matthew 26:47-49 (NKJV), 47 “And while He was still speaking, behold, Judas, one of the twelve, with a great multitude with swords and clubs, came from the chief priests and elders of the people. 48 Now His betrayer had given them a sign, saying, ‘Whomever I kiss, He is the One; seize Him.’ 49 Immediately he went up to Jesus and said, ‘Greetings, Rabbi!’ and kissed Him.”
Thus, Judas permitted Satan to enter him, planned the betrayal, pretended to be loyal, took 30 pieces of silver as payment, and intentionally inflicted pain by Jesus by an evil kiss.
Peter’s denial was completely different. Peter loved Jesus but Jesus’s arrest and trial took him by surprise. Peter followed the soldiers into the high priest’s courtyard and was shocked when Jesus had been found guilty and beaten. Matthew 26:67-68 (NKJV), 67 “Then they spat in His (Jesus’s) face and beat Him; and others struck Him with the palms of their hands, 68 saying, ‘Prophesy to us, Christ! Who is the one who struck You?’” It was then that three different people identified Peter as a follower of our Lord. Peter denied knowing Jesus, because he was unprepared for these events and was probably afraid for his own safety. (See Matthew 26:57-75 for the full account.) After his denials, Peter wept with grief.