It's kinda both. Bulldozer modules have 2 "integer clusters" each, and they stack them up to make processors, 2 for 4xxx, 3 for 6xxx and 4 for 8xxx series. In that sense, a 4100 has 4 distinct processing cores, as it has 4 physical processing elements within its two modules. Each module however, has shared resources which means that you don't necessarily get the same level of performance as you would from a "true" quad core. It wouldn't really be fair to call it a dual core though either.
Intels Hyperthreading works on each core in turn, to effectively use up any leftover space in each processing cycle. It's a very different system. Even in an i7, you only ever have 4 physical cores but you get 8 "opportunities" per cycle to process.