The Pearl White model of the K20 and K20 Pro costs the same as other color variants (check prices here) and you can pick one from Flipkart or Xiaomi's official site. However, at the time of writing, only the base models of the duo are available for purchase.
The Redmi K20 and K20 Pro are identical phones having different chipsets and charging speeds. The vanilla K20 comes with Snapdragon 730 SoC and 18W charging, whereas the Pro variant packs a Snapdragon 855 SoC with 27W fast charging support.
You can read our detailed written review of the Redmi K20 Pro to learn more about it.