Carter BBS - what's the difference in these two

I am absolutely confused and extremely limited in my knowledge. I have a 1964 automatic valiant 225 wagon and would like to install one of these cart BBS carburetors. I can see the physical difference but not sure which one is for my car. Does it matter? The manual refers to one as a spring staged choke and the other a well type choke (i think). The holley 1920 I currently have installed does not have that spring staged feature. So, I am thinking of going with the Carter bbs that also does not have that spring staged feature.