There are a lot of people who may get confused with the difference between 4K and UHD but they have heard of these terms before. When you say 4K, this means that the product will be similar to how the quality will be when you watch in cinemas. When you say UHD, the quality that you can expect is the one that you normally see on television or what you may know as consumer display.
The resolution of UHD is 3480 x 2160. 4K has a higher percentage. In fact, the percentage is about 6% higher than usual. Take note that there are some movies that cannot be shown if the film does not fit the standards that have been set.