A planar ribbon is fundamentally different than an electrostat and, because of that, they sound quite different too.
In both types of drivers, we start with the same sort of plastic substrates like Mylar or Kapton, but there the two radically depart. To make a ribbon driver we need to layer on a thin sheet of copper in the form of a coil, then add tension to this diaphragm and suspend it between powerful magnets. For the electrostat, we coat the substrate with a microscopically thin layer of conductive material (like graphite), add tension, and then sandwich between two sheets of perforated metal.
In both designs, our goal is to move, in cadence with an electrical signal representing music, as thin and lightweight a sheet of plastic as possible. Between the two designs, the electrostat wins the race for low mass and thin but, as with everything in engineering, it comes with both the good and the bad: faster transients at the expense of dynamics and loudness.
Fundamental differences between design approaches exist to explore the extremes of what is possible. From those explorations are born whole categories of product types.
Some of our very best choices are made when we pick and choose between what works and what doesn't. I remember one of the first high-end systems I ever fell in love with. It featured Jantzen electrostatic panels for the tweeters—perfect because at tweeter frequencies we don't need dynamics or loudness. When it came to the midrange, ribbons were used and, for the bass, dynamic drivers. The owner of that system had taken advantage of three fundamentally different designs to build upon their strengths without suffering their downsides.
The point is giving yourself permission to mix and match the best of what works even if they are fundamentally different.