The parameters and statistics are part of the same branch only. The only difference is that they are used to calculate and study different data sets.
The parameter takes into consideration the complete data set or the complete population while studying.
Statistics takes into consideration only a sample data of the whole of the whole of the population.
So, the basic and very important difference between parameter and statistic is that the parameter works on the complete population. And statistics work on sample-based datasets while doing the studying and analysis.