As the name suggests, a dog trainer will help to train your dog. The focus is on following specific commands like sit, stand, fetch and paw, as well as instructions such as those for agility training. A dog trainer can work with dogs individually, with their humans, or in classes for different periods of time. Generally if a trainer is working with a dog to train it to socialise within a family context, the training is much shorter than if it is for professional or support purposes, and in most instance, dogs that are being trained as support animals or for other professional purposes, also require that the trainer has behaviourist and other training too. The extent of a dog trainer’s own training varies significantly, but most dog trainers have completed at the very least a short course, and then build up their expertise through practice.
A dog behaviourist on the other hand, completes more in-depth study into the behaviour of dogs. They learn more about the general psychology of dogs, as well as that of different dog breeds, as well as what can impact on this psychology, thereby affecting behaviour. Their work with dogs extends beyond just training and socialising dogs, to addressing the underlying causes of certain behaviours, to bring about behavioural change in a more long-term way. Dog behaviourists are able to successfully help with dogs who are displaying aggression, excessive barking, resource guarding and more, by working through underlying causes such as anxiety.
And there you have it, a very quick explanation of the differences. I hope that this helps with choosing the expertise that best suits the needs of both you and your pup!