I am no expert, but my understanding has always been that fixie or fixed gear is the broad term for bikes with no freewheel. Track bikes are specific for velodrome racing and are recognizable for their square geometry and rear-facing drops. My bike falls into the category of fixed gear conversion, because it is an old touring frame with a fixed gear. I use the term "fixie", though it is not my favorite word, as to not piss off my friends that ride track bikes. Comprende?