One of the primary differences between the BioBag compostable bag and conventional plastic bags is that the former does not last long. When it comes to polythene bags, they are solely made from a non-renewable resource. On the other hand, BioBag products are made from a mixture of certified biodegradable and compostable polymers and starch.. These bags will start to break down after getting exposed to microorganisms, whereas traditional polyethylene bags take many years to break into smaller pieces.