It is a liquid crystal display ( LCD ) panel in which liquid crystals are arranged in parallel. IPS panels are known for their excellent viewing angles and color performance (compared to older TN panels), making them suitable for many usage scenarios, including gaming and office work.
VA stands for vertical alignment, where the liquid crystals are aligned vertically, perpendicular to the substrate surface. As a result, these panels tend to have wider viewing angles than TN panels (but lower than IPS), excellent contrast ratios, and are good at delivering strong detail in gaming (or movie) scenes.
Pixel response time is how quickly a display switches from one color to another, measured in milliseconds. Faster response times result in less motion blur and sharper images of fast-moving scenes in games. Of the two, IPS panels tend to have lower response times, with the fastest panels typically being 1 to 3 milliseconds (some as low as 0.5 milliseconds).
On the other hand, many gaming monitors with VA panels are advertised as 4ms or lower (GTG) values. In fact many VA monitors have overload problems. These lower response times can cause bright artifacts behind fast-moving objects on the screen.
Refresh rate is how often a screen displays an image per second, measured in hertz (Hz). Most gaming monitors have a minimum refresh rate of 120 Hz. Generally, the higher the number, the better performance we see and the smoother the picture. However, we also need an optimal gaming graphics card that can pump out pixels fast enough. In terms of refresh rate, IPS is better than VA.
angle of view
Most IPS panels have up to 178-degree horizontal/vertical viewing angles. This means that if we're viewing off-center content, there won't be much color shift or a drastic drop in image quality until we reach the extreme edges of the viewing angle. While VA panels have come a long way in terms of viewing angles over the years, they're still not comparable when compared to IPS panels.
Compared with VA screen and IPS screen, IPS has better response time, viewing angle and refresh rate. The contrast of the VA is a bit better, though. For specific purchase, you also need to choose the panel according to your own needs.