TPE and TPU as terms are widely used interchangeably even though TPE is actually a much wider group of materials. The term elastomer is also sometimes generally used and this is just any polymer that is elastic. TPEs (Thermoplastic Elastomers) are a more well worn path towards flexible materials. There are different types of these materials; some of them are styrene block copolymers (SBCs) but others can be thermoplastic vulcanized rubbers (TPV) or copolyester elastomers (COPE). TPU is one thermoplastic elastomer which is a block copolymer made from polyurethane (ester or ether). TPE and TPU as terms are widely used interchangeably even though TPE is actually a much wider group of materials. The term elastomer is also sometimes generally used and this is just any polymer that is elastic. Thermoplastic Elastomers and TPUs are very popular bulk plastics. You could find varying TPEs in your shoes, roof, window frames or car. The TPE group is widespread with lots of materials used in it for the core compounds as well as in fillers. Some of these materials contain styrene and many harmful chemicals. Others have been certified safe in many applications. Generally many TPU materials are unsafe when burned and emit toxic fumes when burned. Polyurethanes themselves, however, are also comprised of a wide group of materials with differing safety and toxicity levels. Due to the nomenclature confusion and the widely differing varieties of these materials, I would recommend extreme caution when printing with or using something that is only generally identified as a TPE or TPU because it could be just about anything. Generally with any material I would recommend a fume hood or enclosure (Yes, just because it’s PLA doesn’t mean it is safe). If we compare it to types of food, then saying PLA would be akin to saying, “this is tomato soup.” You can still put a lot of stuff in tomato soup, including poison and it would still be tomato soup. If you have a nut allergy then tomato soup could still kill you because someone could have put nuts in it. There are lots of different tomato soups and all contain tomatoes but they may contain much else besides. Saying that something is a TPU would be like identifying it as a soup. There could be just about anything in it, but we would expect bouillon and perhaps a vegetable. Saying something is a TPE is similar to identifying something as a hot food. Generally, however, these materials have high abrasion resistance and elasticity. Source：https://3dprint.com