DPI (Dots per Inch) and CPI (Counts per Inch). However, the two names are frequently confusing, making it difficult to distinguish between them.
In their natural contexts, CPI and DPI refer to specific things. DPI measures spatial printing or video dot density, whereas CPI is the correct terminology for mouse sensitivity. However, in the world of mice, the two terms are interchangeable. Yes, in the case of gaming mice, DPI and CPI relate to the same thing: the sensitivity of your base sensor. Both terms refer to a number.