Howard Balzer has the details.
Less clear: what it all means.
The way I read it, Bradford gives up some guaranteed money in 2014 and 2015. In exchange, the team gives Bradford $6 million of the $12 million owed to him for 2012 right now, instead of throughout the season. The remaining $6 million is no longer guaranteed.
Not much of a difference, really. Perhaps there is a compelling reason Bradford wants $6 million now instead of later in the year. The team isn't going to release him this season, obviously, so the guarantees for this season aren't particularly significant. The guarantees Bradford concedes for 2014 and 2015 exceed $6 million total. By then, Bradford could be in line for a new deal, anyway.
Bradford signed his deal under the old labor agreement. The new labor deal dramatically cut guaranteed money for top picks. The reworked deal does reduce some of the guaranteed money, bringing it more in line with what the top rookies are commanding under the new CBA. But Bradford is still getting more than top picks are getting now.
Overall, this change doesn't seem to change much fundamentally. Bradford is still the Rams' franchise quarterback.
Update: In speaking with people familiar with the deal, Bradford still gets $51 million in the first four years, with $50 million guaranteed. The future guarantees disappeared, anyway (upon exercise of an option in 2010). Sounds like there were some changes in language, but nothing of consequence.