This question keeps coming up, and I've often been confused about it myself.
Here's a first stab at putting together a comparison based on pics and descriptions on the HI site:
"Wide Khuks"
WWII - The original/traditional model. Available in 16.5" and 18". Wood or horn handle.
BAS - A smaller, pointier version of the WWII. Available only in 15" and only with a horn handle.
Ang Khola - A wider version of the WWII with a single fuller by the spine. Available in 12", 15", 18", and 20". Wood or horn handle.
Chiruwa Ang Khola - A 16.5" Ang Khola with a full width tand and slab handles (wood or horn).
Ganga Ram Special - Like the Ang Khola but with a smoother arch and no fuller. Available in 18" and 22". Wood handles.
M43 - Like a Ganga Ram Special with an even smoother arch, slightly narrower blade, larger pommel and slab (chiruwa) handles.
Malla - Replica of an old design. Thinner narrower blade. Flat spine. 19". Wood or horn handle.
"Narrow Khuks"
Sirupati - The baseline narrow khuk. Available in 12", 15", 18", 20", 25", 30". Wood or horn handles.
Gelbu Special - Sirupati with a deep fuller. Closed cho. Available in 18" or 21". Wood or horn handles.
Chitlangi - Sirupati with two fullers and a very large bulbous pommel. Available in 18" or 21". Wood handles.
Chainpuri - Lightweight version of Chitlangi with smaller pommel.
Kobra - Lightweight version of the Sirupati. Available in 18", 20", 25". Wood or horn handles.
I'm probably missing some and I've probably made a couple of mistakes. I intentionally excluded non-khuks and specials. If anyone wants to expand on this and maybe include side by side pics, that would be great.
Here's a first stab at putting together a comparison based on pics and descriptions on the HI site:
"Wide Khuks"
WWII - The original/traditional model. Available in 16.5" and 18". Wood or horn handle.
BAS - A smaller, pointier version of the WWII. Available only in 15" and only with a horn handle.
Ang Khola - A wider version of the WWII with a single fuller by the spine. Available in 12", 15", 18", and 20". Wood or horn handle.
Chiruwa Ang Khola - A 16.5" Ang Khola with a full width tand and slab handles (wood or horn).
Ganga Ram Special - Like the Ang Khola but with a smoother arch and no fuller. Available in 18" and 22". Wood handles.
M43 - Like a Ganga Ram Special with an even smoother arch, slightly narrower blade, larger pommel and slab (chiruwa) handles.
Malla - Replica of an old design. Thinner narrower blade. Flat spine. 19". Wood or horn handle.
"Narrow Khuks"
Sirupati - The baseline narrow khuk. Available in 12", 15", 18", 20", 25", 30". Wood or horn handles.
Gelbu Special - Sirupati with a deep fuller. Closed cho. Available in 18" or 21". Wood or horn handles.
Chitlangi - Sirupati with two fullers and a very large bulbous pommel. Available in 18" or 21". Wood handles.
Chainpuri - Lightweight version of Chitlangi with smaller pommel.
Kobra - Lightweight version of the Sirupati. Available in 18", 20", 25". Wood or horn handles.
I'm probably missing some and I've probably made a couple of mistakes. I intentionally excluded non-khuks and specials. If anyone wants to expand on this and maybe include side by side pics, that would be great.