Usually the boxes of screws come with the bottom, more silver bit. But today’s box had the duller grey, bit with a green lap band. No idea if one is better than the other or not.
Edit: Thanks to @0x0@infosec.pub for the wiki article!
Bits like that are used for impact drivers
Torx is pretty standard for just about any kind of hardware nowadays. It’s actually more appropriate for construction than delicate electronics as it allows a lot more torque with less slipping. One of the benefits of a Phillips or flathead is that you’ll probably strip the screw before you over torque and break something.