Centigrade and Celsius are similar temperature scales, but the Celsius scale is slightly more accurate. Both scales use water's boiling point as a benchmark at 100 degrees, but they use different measures to determine zero degrees.
Anders Celsius, a professor in Sweden, created his temperature scale in 1741, but his version listed the boiling point of water as zero degrees and the freezing point as 100 degrees. After he died, the scale was switched to its current form and called the centigrade scale. Because of Celsius' role in inventing the scale, people referred to it as Celsius' scale, which can cause confusion.
There were problems with this scale. The most important was that it was based on a value that could not be determined accurately enough for a measure as important as temperature. In the 1950s, the General Conference of Weights and Measures set out to standardize several units of measure, including temperature. It was decided that the scale should be based around the triple point of water. The triple point of water is when it exists as a liquid, solid and gas at the same time. This can be measured more accurately than the freezing point, so the scale was refined to fit it. Because of this redefinition, it was given a new name, the "Celsius temperature scale."