These are 5 that I see:
1. LOCATION: The guys had just arrived in chapter 1 and stayed over night right there in the clearing by the pool. They meet again in this place during chapter 6 that they had agreed upon in case there was trouble.
2. PURPOSE: The whole reason they end up in this location twice is because Lennie had done a bad thing. Both times they were running from Lennie's crimes to women that are derived just from a desire to touch soft things.
3. THE DREAM: Both chapters have the two friends talking about the dream of their farm they will one day have... almost as if they can see it.
4: FAMILY: During both instances George takes the role of a father figure doing what is right in terms of tough love. Lennie takes the role of the child acting in obedience as best he can and taking punishment whether he chooses to or not.
5. PEACE: In chapters 2-5, we encounter the struggles relationships require. By the time we get to Lennie's death scene in 6, and before they left the location in chapter 1 for the ranch, the two friends sat in a tranquil, unencumbered mood.