The climate is cooler at 45 degrees latitude compared to 0 degrees latitude because the Sun is shining at a different angle. At 0 degrees latitude, the Sun is shining directly overhead, and thus it receives highly-concentrated sun rays which heat up the Earth rapidly. However, at 45 degrees latitude, the Sun is shining at a slanted angle, which makes the sun rays spread over a larger area and warming the Earth at a slower rate.
