TIA-422, TIA-644 specs contain excruciating detail for you
to absorb.
RS-422 is more fault tolerant and a nominal 4V difference.
RS-485 is additionally fault tolerant. LVDS is for a shorter
haul and a more electrically benign environment.
There is not an "exactly" difference voltage, there is a
range of allowed "must produce" at the transmitter and
a "must accept" at the receiver.
RS-422 is something like 2V min output diff and 400mV
max input diff. LVDS, 200-250mV and 50mV if I recall.
You can look it up or refer to manufacturer datasheets
and app notes for 26x31/32 (RS-422) and 90x31/32
(LVDS) families.