It is (almost certainly) the same kind of guinea pig. Ideas of what constitutes optimal care differ between regions and over time. The reasons for housing guinea pigs indoors are outlined in this thread and the links at the bottom of it:
http://www.guineapigcages.com/forum/...g-outside.html
There are always some guinea pigs that manage to live (seemingly) healthy, long lives while kept outside, but that does not mean that this is best for them or that most guinea pigs kept outside fare well. On average, guinea pigs kept outside live shorter lives, and they also generally receive less attention. In addition to providing a more constant temperature and a less drafty, less stressful environment, indoor living also removes risks such as predators (including people). I hope that explains things a bit. Your 3x5 cage with some supervised time outdoors sounds excellent!