The text didn't state. It doesn't list DCs or anything, and was rather vague. hence the question. so.. Is there a DC change for pin vs grapple? in grapple, if youre the grappler you get a +5. Does it improve for a pin? (Id assume yes, but pin had little written about it for mechanics.)
It doesn't list DCs because it's an opposed CMB vs CMD check. Pinned is a condition, not a separate state as far as grappling is concerned. Imagine being
shaken while in a grapple. The rules don't change... you've just got additional restrictions on your behaviour.
Meanwhile, since you're pinned, your grappler gets a +5 bonus on subsequent rounds because nothing changes for him that would alter that. If there's no statement that something changes or improves, it doesn't.
Basically, if you get grappled, you're in a sorry state and can do a few things including try to break free. If the creature grappling you pins you, you're in a worse condition but can still try to break free of the grapple by using the same mechanic. Once you're not grappled, you're also not pinned because you're free.
Don't think of pinned as a layered "deeper grapple" like it was in 3.5 It's now just a condition where your choice of actions are reduced. The purpose behind pinning someone is so they stop attacking you and/or casting spells, not to make it harder for that someone to escape.
These are the relevant bits:
Grapple: If your target does not break the grapple, you get a +5 circumstance bonus on grapple checks made against the same target in subsequent rounds. Once you are grappling an opponent, a successful check allows you to continue grappling the foe, and also allows you to perform one of the following actions (as part of the standard action spent to maintain the grapple).
Pin: You can give your opponent the pinned condition (see Appendix 2).
If You Are Grappled: If you are grappled, you can attempt to break the grapple as a standard action by making a combat maneuver check (DC equal to your opponent’s CMD; this does not provoke an attack of opportunity) or Escape Artist check (with a DC equal to your opponent’s CMD). If you succeed, you break the grapple and can act normally. Alternatively, if you succeed, you can become the grappler, grappling the other creature (meaning that the other creature cannot freely release the grapple without making a combat maneuver check, while you can).
Pinned: A pinned creature can always attempt to free itself, usually through a combat maneuver check or Escape Artist check.