(Sigh) Alright, due to everyone bickering it might as well be said.
The final episodes of the Series were animated due to budget constraints and delve into a LOT of psychology. Shiji is forced to face the differences between perception versus reality by Instrumentation. You can say this all takes place in Shinji's mind/ or between his soul and the people closest to his heart. The episodes only include him coming to terms with himself and why he rejects the false-self.
Death and Rebirth recap and start the End of Evangelion. End of Evangelion is what many consider what happens in the moments directly before Instrumentation and includes a simplified explanation of what goes on during it. Rather than go into the mind of Shinji, we're looking at this from the 3rd person's advantage. We see Shiji favored by Lilith/his Mother/ Rei and given the ultimate decision of not only his life, but the fate of the Human race. There is a huge amount of animated gore. If you're relatively sheltered (doubtful considering you're on 4chan), then the movie might shock your beliefs and senses.
The EoE movie is suggested watching. It has some neat fight scenes and helps you understand some of the nuances of the storyline.