Southie and Charlestown are very different. The population of Charlestown is less than half that of South Boston. Charlestown is about a mile square, so much smaller. Both are contiguous to downtown Boston with Charlestown to the North. Southie has a more vibrant restaurant scene, but Charlestown has a much tighter neighborhood feel, and you are never far from services and restaurants. I have been an agent for 20+ years, and I live in Charlestown, so I am a little bit partial, but I think it depends on the 'vibe' that you are looking for. Charlestown is a mix of young couples with kids and young professionals, as well long time residents and has become a spot where familiesdecide to 'stay' in the City.