Some explanation of the differences in straps; i.e. a "jerk" strap vs "tow" strap vs air "sling" strap.
I don't think there are exact rules or specifications for it but this seems to be the general guide lines.
Tow strap -
Usually the ones with hooks and rated for 7-10k lbs. Like the name states its intended for towing, meaning more static loads like for example, towing a vehicle not moving under its own power, down the road and not stuck, or held back in any significant way. It is NOT for recovery or freeing stuck vehicles if any serious force is needed such as yanking. Basicly if you have to have slack in the strap and use momentum of the recovery vehicle to move the immobile rig then its the wrong applicaton for a tow strap.
Recovery strap -
The ones with loops at the ends and designed for yanking or a kinetic type of load. Ones for offroad use are normally rated for 20k or 30k lbs. You might want a higher rating if you have fullsize trucks. They are intended to use momentum of the recovery rig, by having a little slack in the strap, accelerating to gain the momentum, then when the slack is pulled tight it streches to absorb the hard initial impact, and then acts somewhat like a rubber band where it wants to contract helping to pull out teh stuck vehicle.