Strictly speaking, there is a fundamental difference between the two.
A "touchscreen" is merely a hardware component that may be used in an HMI product; it's an input device installed in front of a display screen, replacing some functions of a mouse and keyboard.
An HMI product, on the other hand, is a human-computer interaction device that includes both hardware and software.
In industry, HMI products with touch input capabilities are often referred to as "touchscreens," but this is inaccurate.
