I managed to acquire the second Carrigan's quart from a deceased estate. Here are the two together. The differences are subtle but the more you look the more you'll spot. To get you started, check the second R in Carrigan's, the letter G's & the apostrophe...
Two generic half gallons. The straight one on the right is the same as a McJunkin Straight half gallon (same text on rear) except for a blank slug plate. The bowling pin on the left is embossed 2 QUARTS and has no slug plate. None of my other half gallons are marked 2 QUARTS & none are bowling...
Three different sizes of Dr Brush's ambers - scan of an old photograph that I acquired from a deceased estate. This is the only evidence I've ever seen of the medicine bottle style half pint cream bottle.
I picked up an undocumented Windsor Farm quart variation recently. Here are my two together indicating the difference in alignment of the top & bottom words.