Taken from wikipedia
Hope this helps and also there is no 120hz for 1080p so either way you wont get 120hz
1080p is the shorthand name for a category of display resolutions. The number "1080" represents 1,080 lines of vertical resolution,[1] while the letter p stands for progressive scan (meaning the image is not interlaced). 1080p is considered an HDTV video mode. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels. This creates a frame resolution of 1920Ã-1080, or 2,073,600 pixels in total. The frame rate in Hertz can be either implied by the context or specified after the letter p, such as 1080p30, meaning 30 Hz.
Due to bandwidth limitations of broadcast frequencies, the ATSC and DVB have standardized only the frame rates of 24, 25, and 30 frames per second (1080p24, 1080p25, 1080p30). Higher frame rates, such as 1080p50 and 1080p60, could only be sent over normal-bandwidth channels if a more advanced codec (such as H.264/MPEG-4 AVC) were used. Higher frame rates such as 1080p50 and 1080p60 are foreseen as the future broadcasting standard for production.