Sierra is the name used by Berea Hardwoods. . "Same" style and size from PSI is the Gatsby. . These are probably the two most common.
There are a large number of variants which are generally compatible as to the diameter/length of brass tube used.
Some names of variants are Diplomat, Pioneer, Ellipse, Thank-You pen, ......
If you want to ensure compatibility you'd have to ask before you buy.
As for other pen styles, another which is commonly duplicated is the Cigar, again by Berea. . PSI sells theirs as the Big Ben. . Again there are others.
And, again, you have to check compatibility before buying .... there are some variations, mainly in the lengths of the brass tubes, and also in the diameter to which you turn your blank in order to match the hardware at the nib and finial ends (ie. bushing size if you use bushings).
BTW, the Berea Cigar pen is often referred to, even on their website, as the Extra Large Twist pen, or as the Fat pen.
There are tables of pen kit specifications in the IAP Resources section. . I believe there is a table for each major pen kit supplier.
It is a time-consuming process, and it requires some computer skills at searching these files, but you can come up with the information that you require by consulting these tables. . I don't know of anyone who has done this in a systematic and comprehensive way and made their results public.
For most of us, this kind of knowledge comes through much experience over many years, coupled with frequent visits/questions to IAP !