I have posted this before, I do not have the same photo uncapped, I will have to take it sooner or later...
from left to right
Ranga 5 mottled brown
Ranga 3 (flat top) mottled green
Ranga 4C (rounded ends) pink swirl bakul
Ranga 3C olive swirl bakul
Ranga 3C olive swirl polished
Aurora Talentum (as size comparison)
The main difference between the 3 and the 4 (whether C or not) is the step down between section and barrel.
The 4 has the step down the 3 does not.
That looks good on the 4 when the pen is closed (flush)
But can be annoying depending where you place your fingers. The 4 still has quite a long section so it is unlikley your fingers will be on the step down. My preference still goes to the 3 for the lack of step down.
here is the 4
and the 3