could anyone with expertise with these breeds please give me some general information about the differences in  their tempraments and personality. I have a relation who has firm ideas about these breeds and would love to be able to discuss it more. I know the bull mastiff comes from the mastiff and they are different physically.

From what i know of Dogues they need a lot of hard work within the first 12 to 18 months of their life as they can have a high prey drive.  I wouldnt reccomend them for the first time molosser owner.

Bullmastiffs need some amount of training but from experience they tend to have a much more laid back attitude than the DDB.