Star Trek: 10 Biggest Differences Between Kirk's Enterprise And Picard's

Holographic communication devices existed in Kirk's time, as we see in the Star Trek: Discovery episode, The Vulcan Hello, but they had poor resolution, and at this time, the holograms were merely 3-D projections of people that could not actually be touched. They fell out of use before The Original Series and it wasn't until about a hundred years later that we started to see some advancement in the tech.

The Next Generation's pilot introduced us to the holodeck, leaps and bounds beyond the holograms of old, able to render entire realistic worlds that fit within the confines of a small room, yet appear to stretch beyond the horizon. The holodeck employed an extremely advanced system of lasers, force fields, optical illusions, and anti-gravity to make the simulated worlds indistinguishable from reality.

The creation of the holodeck was the greatest advancement in entertainment in human history and, by the late 24th century, they were onboard nearly every starship in the fleet, every starbase, and even some people's homes.