The term "2K" refers to any display or content with a horizontal resolution of approximately 2,000 pixels. Depending on whether you are in a cinema or at home, the exact dimensions change:
Standard Blu-rays are 1080p. To get higher quality, you typically jump to 4K Ultra HD Blu-rays, which often use 2K master files "upscaled" to 4K. 2k movies hd
Here is why is the practical winner: