It's really simple. A "path frame" is the same thing as a "track frame." A "path racer" is simply a track bike. A "road/path" frame or bike, OTOH, would usually (though not always) have rear-facing dropouts, a lower bottom bracket, minimal braze-ons, and a bit more relaxed geometry overall. It was legal for track racing, but could also be used for training on the road, time-trialing, club runs. Some tracks were grass, some were paved, but this apparently has no bearing on the use of the term "path" vs. "track." Usually, when folks use the term "path racer," they're actually referring to a "road/path" bike.