I'm going down later this year to play Congressional, but my understanding is that the changes are pretty extensive.
All the greens were rebuilt, and some were regraded and reshaped and recontoured.
Many new tees were added, some at much different angles than previously.
Fairways were recontoured to create "upslopes" in the driving areas, to retard the rolling of the ball.
Not sure about bunkering...all this is second-hand information from a person I know who just played there after it re-opened and is well familiar with the course.
He says it's a beast, which is not surprising if they are trying to re-re-re-toughen it again for high-level tournament play.