A monitor is a screen which displays the visual output from your computer. There are many features of monitors to consider, these include the inputs, screen size, screen resolution, response time, wall mountable.
A touchscreen is a monitor where the screen can detect the presence and location of touch on the display area by finger pressure. Some touch screen devices can also sense passive objects like a stylus. Connectivity for the visual part of the monitor is via the usual interfaces such as VGA, DVI or HDMI depending on the specification. The touchscreen connectivity is via serial or a USB connection to the computer system. The computers operating system has to support touch screen functionality in order for the touch to screen to work.