The European Bioplastics Association defines bioplastics as being biobased, biodegradable or both. And PLA bioplastics are the only commercially available bioplastics that are both biobased and biodegradable!
What are biobased plastics?
These plastics are made from biobased, renewable materials like corn, sugarcane and cassava. These feedstocks are often referred to as biomass. Biobased plastics can be used for almost any application, from molded parts and fibers, to foam & film. Plastics in this category include PLA, Bio PET, Bio PA and Bio PE. They enable products that have a reduced carbon footprint and a high biobased content.
What are biodegradable/compostable plastics?
Biodegradable plastics are those which biodegrade in natural environments leaving behind biomass, CO2 and water. They are sometimes made from traditional fossil fuels (such as PBAT) though can also be made from biomass (such as PLA). PLA meets the widely recognized European compostability standard EN13432.
NOTE: Oxo degradable plastics are made from traditional fossil fuels and include an additive that makes the plastic degrade under UV sunlight. They fragment into micro-plastic pieces and conclusive evidence has yet to be presented that these fragments fully biodegrade. Not surprisingly, many believe these oxo plastics are worse for the environment than traditional plastics. So oxo degradable plastics should not be confused with bioplastics. Recently, three manufacturers of oxo degradable plastics took exception to a proposed multi-client study by OWS to investigate whether or not oxo degradable plastics are indeed biodegradable. (See http://www.plasticstoday.com/articles/three-manufacturers-of-oxo-degradable-plastics-take-exception-to-projected-OWS-study-140922)