The BMW 5 Series and the BMW 3 Series are both popular models from the BMW lineup, but they are designed for different segments of the market. Generally, the 5 Series is considered as a more premium car compared to the 3 Series, and it offers more advanced technology, features, and options. In terms of price, the BMW 5 Series is typically more expensive than the BMW 3 Series. Also, the 5 Series is bigger in size than its sibling.