A "portable" version is a repackaged executable that bypasses the Windows installer. It forces the software to run directly from a folder (usually on a USB drive or external SSD). When you unplug the drive, no trace of the software remains on the host computer.
Version 2019 is now considered "legacy" by Corel. The official version no longer receives updates. The portable version never did. You will miss critical bug fixes and security patches.
If you are exploring 2019 specifically, there are a few other features introduced in this version that are highly useful:
