big boys coming home, page-4

The announcement says,

· AGL increasing its subscription price for QGC shares by 16 cents, up to $1.60 per QGC share for a 27.5% investment in the company.
· A QGC tender buyback of at least $1.52 per share.

What's the difference between "subscription price" and a "QGC tender buyback" price ($1.52)?