Numeric displays used in real aircraft may have different types of indicators, which may be based on LCD or LED. However, displays used in older equipment may have Gas Discharge, Fluorescent or Incandescent indicators, and even electromechanically controlled rotating numeric indicators.
Most of them (except the mechanical ones) use seven light "segments" to display digits. and can be replicated in your home cockpit using 7-segment LED indicators, which can be a fairly realistic replacement, especially if you can find indicators of the right size and color.
The term "7-segment" is related to the form of displaying numeric information, and does not define the type of the display itself, its construction and operation.
Another option is to use LCD displays, which can usually display multiple numeric parameters and letters.
Please note that in addition to 7-segment indicators, aircraft equipment may use 9, 14 and 16 segments for alphanumeric characters, which can only be replicated in the SimVimX system using character LCDs.
