It all comes down to how you use the terms. Generally, you can think of them like this:
Rubber playground tiles: Installed as the flooring of the playground area.
Rubber playground mats: Used at specific places on the playground, such as at the bottom of slides, under swings, etc.
You can typically buy and install rubber playground mats yourself, but will need a professional installation company to install rubber playground tiles as the flooring/surfacing. Note that on our site, we use the terms interchangeably.