Basically the pollen filter, will filter as it states pollen and dust and generally other particles were it be leaves etc.
A charcoal filter does all the above but has anti allergy components built into the material as well as stops odors like exhaust fumes, leaky oil smells from your engine bay and basically any un-pleasent odors from entering the cabin.
Also charcoal filter the material is treated with chemicals were as a normal pollen filter is just material hence the extra price.
Same thing with when it comes to bed pillows and duvets that it has anti allergy resistance or how ever you want to word it.