Lifestyle photography mainly aims to capture portrait/people in situations, real-life events or milestones in an artistic manner and the art of the everyday. The primary goal is to tell stories about people and inspire others in the process.
Street photography can tell such a powerful story. Because it is not a posed image, it captures beauty in the raw emotion of the moment. It's not always easy to ask a total stranger if you can take their photo, but it is so worth the momentary discomfort.
While the two seem very similar and do overlap a bit, the nuances of the individual style & story set them apart.