Sorry, but I disagree with the statement both are safe. I never use plastic for cooking. Even the Ziploc Bags are not safe unless labeled as safe, and most are not. Only a few are labeled for steaming and/or microwaving (yuk!). Even BPA-free plastics contain harmful synthetic chemicals. They also use many colors/dyes in their products. Any of these may leech into your foods. Most are only labeled as safe for food storage and/or freezing.
FoodSaver bags are better (made for simmering/SousVide), but still made of plastic (polyethylene).
I use the Stasher silicone bags. They are safe at high temperatures and reusable. A bit more difficult to wash sometimes, but worth the safety and savings. You will get a 20% off certificate with your first order and can use that continuously thereafter. I'm waiting for them to create a larger bag. One gallon is their largest.
These silicone bags work just like regular plastic bags, they are pinch-press and air-tight. They are also petroleum free, contain no PVC, latex, or phthalates. The bags' non-porous surface inhibits bacterial growth. Silicone is inert, it does not react with other elements or compounds.
You can check out the SCJohnson.com and FoodSaver.com and StasherBags.com websites and make your own comparisons.
Just my two cents!! (Smile)