IPS (in-plane switching) is a newer method of orienting electrodes and therefore liquid crystals with-in the LCD screens. IPS technology is an improvement and a replacement for the legacy TN (Twisted Nematic) and its main advantages are much better viewing angles, improved color accuracy and a decreased color shift when viewing the screen from the sides or from above.
IPS and TN panels can in most cases share the same electrical/data signalling interfaces and therefore can be mutually substituted. Some laptops may have offered IPS as a premium upgrade and some laptops (low to mid budget category) were only shipped with TN panels. The fact that any particular laptop was not originally shipped with an IPS screen, or that the IPS option was not offered by the vendor at a point of sale does not preclude the use of an IPS screen for a replacement.
Provided that the connector is the same, usually a 30-pin eDP, IPS panels can be used in-place of a TN panel with dramatic improvements to image quality.