There have been minor improvements to driver technology over the last decades, but it hasn't been much. I asked basically this same question a while back and people said the driver itself doesn't make that much of a difference, everything else makes the difference. The biggest thing that impacts sound is the housing design, the shape of it is normaly determined by trying out lots of shapes and seeing what works best. This is also how headphones are tuned to get their unique sound.

The driver still makes a difference. A good driver is going to perform better than a cheaper, smaller driver. The material also matters, lighter materials are able to move faster and distort less at high volumes. The magnets make a difference too. The difference is tuning, even if 2 headphones have the same driver, companies can modify the magnet type, housing, angle, and material to get drastically different sounds.

Some people have also experimented with driver shape. Focal headphones have a M shaped driver, and the Sony Linkbuds had a ring driver. But those are expected to sound different.