As with all hand made blades, there is some variation from one Chainpuri to another, even at the same length. In general, the Chainpuri is functionally similar to the Sirupati and Chitlangi, with some cosmetic differences in the handle and fullers.
I believe this design originated in parts of Nepal where people have to deal mostly with brush and slim trees; thus, the Chainpuri is not a heavy chopper but is well suited for just about everything else, including self defense or martial arts.
Chainpur is a town or province (I'm not sure which) in Nepal that is well known for excellent blademakers and for this particular design. It is the only place, as far as I know, where HI often buys Chainpuri knives to sell here. They are selected to ensure quality and Yangdu always describes them as such. A blade from Chainpur does not have a kami mark or initials, unlike HI-made blades that identify the maker. HI kamis also make this model, such as the one you just got by Purna.
As far as cosmetics are concerned the Sirupati is probably the simplest and the Chitlangi the most elaborate, with the Chainpuri in the middle.