A tempeature sensor can tell you if the product you are canning has been processed to a high enough temperature to destroy bacteria, or it could be applied to the line to check each can that passes to be sure it has been filled to the proper level with the hot material. It can also tell if the product has been chilled enough for placing into cold storage, or whatever the next step in the process may be. Pressure sensors tell if the can is in place under the injector to let the machine know it's OK to fill the can (because there's a can there to fill), it can also check that the fill is to the prescribed weight. A pressure sensor lets the bottler know when to stop adding carbon dioxide to the can or bottle of Coke or Pepsi. Basically, the pressure sensor tells how much a component weighs, whether it's in place or not, and in some cases, if it's positioned correctly for whatever the next step may be. The temperature sensor tells the actual temperature, distinguishes between air (at ambient temperature) and nearly anything else that's either hotter or colder than room temperature, and can tell if thermal conditions are above or below a given specified range.