I never really understood the difference between the two and why Kodi defaults 59.94Hz instead of 60Hz. ¯_(ツ)_/¯
59.94Hz is the NTSC refresh rate standard common in USA:
59.94Hz is used because it’s the actual refresh rate used for TV in ‘60Hz’ areas like North America, Japan, Korea etc…
When colour was introduced to the NTSC US B&W TV standard in the 50s, they had to alter the line standard from 525/60Hz to 525/59.94Hz to avoid the colo(u)r subcarrier potentially interfering with the FM sound carrier (The colour subcarrier is precisely locked to line-rate, and they couldn’t change the number of lines per field or the FM sound carrier frequency, so the only option was to subtly alter the field-rate to alter the subcarrier frequency)
This is why we have 59.94, 29.97 and 23.976Hz refresh rates rather than 60/30/24…
60Hz is not used at all for broadcast video (the Japanese initial analogue HDTV system tried to switch from 59.94Hz to 60Hz - but conversion from 60Hz HD to 59.94Hz SD was a real pain), and 24.000Hz is really only used for some Blu-ray transfers of movies and streaming services of the same transfers. There was, again, a proposal for UHD and UHD2 services to be just 60Hz or 120Hz, but 59.94Hz and 119.88Hz have been retained as well.