Answer: In observational study observer has no control on the variables but in an experiment experimenter has control over the independent variable to record the change on the dependent variable.
Explanation:
In statistics , an observational study is a study in which a researcher just observe effects on subjects in a certain manner without interfering them.
On the other hand an experiment is a process which is done by experimenter to demonstrate a known fact or create a discovery by applying some methods to the variables .
The basic difference between an observational study and an experiment is in observational study observer has no control on the variables but in an experiment experimenter has control over the independent variable to record the change on the dependent variable.