Different battery manufacturers will arrive at different ratings for the same battery. Ya think I'm kidding? Not counting Taiwan/China imports, nearly every car battery sold in N. America comes from one of two makers (Yuasa-Exide or Johnson Controls), including OEM and big retailers. Within a specific manufacturer's line, the higher number has meaning. Judge a battery by its warranty period. The higher quality batteries carry a longer term, and you'll notice that they are also the ones with the higher rating. Stick with the correct BCI type and you can't go wrong. Volvo did not undersize the recommended type.