Einstein received the Nobel Prize for his work on the photo-electric effect rather than for relativity due to the Nobel committee's preference for experimental validation over theoretical concepts. The photo-electric effect had a direct experimental connection, making it more favorable for recognition. In contrast, theories like special and general relativity were seen as less experimentally grounded at the time. Additionally, the Nobel committee's political considerations may have influenced the timing of awards, as seen in the delayed recognition of other quantum theorists. Ultimately, the distinction highlights the committee's focus on fundamental physics that can be empirically validated.