As mentioned, the Black Widow originally had a "stunt vented" tank with fully extended fill and vent tubes mounted on the tank, and a ventless backplate.
The Babe Bee originally had tank fill and vent nipples on the backplate, later ones have a fill nipple and a vent hole. The backplates with the vent hole were originally metal but later were plastic.
The Texaco that I have uses a red ventless metal tank and a plastic backplate with fill nipple and vent hole. There may have been other iterations of that also, plus the Texaco Junior which has a smaller tank.
Venturi sizes varied depending on the purpose. That is, the Babe Bee had one size for better handling, Texaco was sized for good fuel draw at low RPM, and the Black Widow was sized for power.
Just before ESTES shut down operation, I'm not sure you could tell differences.
George