Carrera Vulcan, which review is correct ?

They are both the same bike, the specification can and will change from one shop to another and how long the bike has been sat in the warehouse. When you go in to Halfords it will probably not be the same as the advert.

“Specification subject to change without notice”

This is an entry level mountain bike and you won’t find a better one for £200
If you can do the basics yourself when it comes to maintenance get a bike from Halfords as after sale support is not very good at some stores, otherwise LBS and it will have to be a different make as Carrera is exclusive to Halfords.

You have posted for 3 months about what bike to purchase and still not got one, its £200, any cheaper and they will have to give them away.

Just go and buy it ………..