I often wondered why RE USA had both the B5 and C5 models.
They are different and appeal to different people.
The B5 is pretty much the original UK designed 1950's bullet and uses the original 1950s British frame wheels etc (but has a disk brake and with a more modern engine shoehorned in to meet modern emission/noise requirements) and B5 parts and accessories will often bolt straight onto a 1950's bullet and visa versa.
The C5 is not an original British Enfield design - it is an Indian retro styled design based on the original Bullets. It is more akin to the current flock of Harley/Triumph retro bikes, bikes designed for people wanting a retro look and feel but not overly interested in how authentically they resemble genuine original vintage/classic bikes.
In a sense the B5 is much closer to what a 1950's British Bike actually was (albeit with modern engine and disk brakes) whereas the C5 is more representative of what the average person thinks a bike from that period should look like. For example the C5 has a late 1950's style swing arm rear end but the wrong sized wheels for the 50's (and in later versions even has more modern straight forks) and has a solo seat that was much more common on plunger/rigid bikes from the 30's and 40's . The C5 is a fine bike and I would happily own one, but its much more about looking like what people expect a 50's bike to look like than anything else.
By the way ... you can also expect the current Himalayan to disappear later this year because a 650 twin version has already been announced.