Do Phillips ALTO florescent bulbs save energy? Or are they just known for having less mercury. I would assume they would use less energy. I’m just curious.

Philips uses the Alto label for reduced mercury.  Econ-o-Watt, and more recently, Energy Advantage are for reduced wattage.

So would the ALTO bulbs cost the same as a regular tube?

Yeah, in fact it seems like with Philips and others there often isn't a choice.  A given lamp size and color is typically either low mercury or not.  There's rarely a low mercury and full mercury version of the exact same lamp available for price comparison.