The perceived frame-rate will be smoother on a 60hz Freesync Panel on vs off. This will all depend largely on the variable refresh rate (VRR) range of whichever monitor you're referencing has.
Say it's a 60hz panel with a VRR range of 40-60hz (typical of many cheap panels or some of the more basic 4k panels). What Freesync, Gsync, or any Async based panel tech will do is match the monitors refresh rate to the FPS you're running your game at. As long as your FPS is within the range of your panels VRR range, in this case 40-60, you'll see smooth gameplay and shouldn't notice any hitching or stutter due to FPS changes.
Now if you disabled freesync, gsync, or async, and enabled vsync, there wouldn't be any tearing but you may notice a lot of stutter, hitching, or the gameplay may seem choppy to you at sub 40-50 FPS; afaik with vsync you'll also be introducing latency.
One other important thing when it comes to freesync is making sure that you can either run all of your games at FPS within the monitors VRR range, or you find a panel that supports LFC. LFC will double the refresh rate of the FPS once you drop below the minimum VRR range. In this case say you had a monitor with a VRR range of 30-90hz. If you drop below 30 fps in game, say to 23fps, the monitor will now run double the refresh rate while freesync is active -> 46hz. While LFC isn't perfect it will still make gameplay sub 40 fps much smoother.
I hope that helps, I'm too tired to explain any better at this point
. I'm sure someone else can provide a much more in depth description of certain aspects.