Pats fan here. My understanding was the difference was everyone else was videotaping from the first row of the stands, which was legal. The Patriots were doing it from the sidelines, which was illegal.
Every team was doing it. Why do you think the offensive coordinator and defensive coordinator cover over their mouths with a plastic sheet. It is to keep the other team from reading his lips as he speaks into his microphone. All teams employ lip readers for just this purpose.
It is amazing what teams will go through to gain an edge in the NFL. You might have noticed that teams now issue their players tablets (such as the iPad) to store their game plans and game films. In the past, teams were paranoid about their playbooks being copied and given to another team. Especially when players got traded.
With the tablets, the teams now have the ability to remote erase them if they are lost. These tablets are locked down so tight that players are unable to backup the data or print it out. And if they try, every keystroke is recorded so that the team's security will immediately find out. I believe players have been fined severely for even the slightest misuse of their tablets.