1080p 1080i 720p (IE the i/p suffix) denotes a SMPTE resolution and timing.
HD/FHD/UHD (720,1080,2160 respectively) also denote SMPTE resolutions and timings.
These are SMPTE ST2036-1 standards, which are 16:9 and have defined (but not arbitrary) frame rates up to 120fps.
4k DCI is still a SMPTE timing, but used for cinema and is generally 24fps (tho can be 48fps for 2k DCI).
It’s SMPTE 428-1.
There are other “4k” standards, but not nearly as common.
If you have arbitrary resolutions or timings outside of the SMPTE standards, and generally fall into VESA standard resolution/timings or custom EDID resolution/timings.
Chances are your computer is actually running 1920x1080@60 CVT-RB rather than 1080p60.
Whilst 1080p60 and 1920x1080@60 seem like they should be the same, some displays (and devices) might only support SMPTE timings or VESA timings.
So, although a display is 1920x1080 it might expect SMPTE, but the device can only output VESA.
1080p 1080i 720p (IE the i/p suffix) denotes a SMPTE resolution and timing.
HD/FHD/UHD (720,1080,2160 respectively) also denote SMPTE resolutions and timings.
These are SMPTE ST2036-1 standards, which are 16:9 and have defined (but not arbitrary) frame rates up to 120fps.
4k DCI is still a SMPTE timing, but used for cinema and is generally 24fps (tho can be 48fps for 2k DCI).
It’s SMPTE 428-1.
There are other “4k” standards, but not nearly as common.
If you have arbitrary resolutions or timings outside of the SMPTE standards, and generally fall into VESA standard resolution/timings or custom EDID resolution/timings.
Chances are your computer is actually running 1920x1080@60 CVT-RB rather than 1080p60.
Whilst 1080p60 and 1920x1080@60 seem like they should be the same, some displays (and devices) might only support SMPTE timings or VESA timings.
So, although a display is 1920x1080 it might expect SMPTE, but the device can only output VESA.