I don't think your activity will accept Page as a Parameter if you check in the Data type of your parameters in activity. You wont see the Page type option in the Parameter Data type, can you brief what your are trying to achieve so that we can help you.
If you want to pass any Object then you can use ParameterPage.putObject("ParameterName", "Value");
For example, in your activity if you want to call another rule which has the required parameters then in your activity you might be setting the parameter values based with the help of property-set methods and during the call of the another rule we will get the option to set the parameter values over there or we can pass the current parameter page to the called rule. For example, while calling Call Rule-Obj-report-Definition.pxRetrieveReportData we will use the Pass Current parameter page checkbox by setting its required parameters in previous steps.
In case of individual passing parameters, it doesn't mean that the parameters alone can be passed to the another rule as internally it will also stored in the Parameter page itself even though you declare them in Parameters tab. I am not sure what kind of difference you are looking for among this two ways of parameters passing.