@AbhishekC1725 svcAddWorkObject will create work object for you.. NewFromFlow and pxCreateTopCase will also create case for you.

1. If you want to just create case by passing the case type class and flow class, then use NewFromFlow.

2. If you want to create case and copy data from current case to new case and do some kind of data manupulation, you can use pxCreateTopCase. Activity will input Data transform rule as a parameter. You will also have a OOTB behaviour to store created case id to the current case property.

3. If you want to use create case and use advance features, use  svcAddWorkObject , like passing Coverhandle as parameter(created case will be created as subcase), perform security validation(by passing returnNextActionInfo as true in with parameters) -> whether current user has next assignment to work for the newly created case. If yes,CurrentUserHasOwnership will be set as true in the background. If you want to skip create view for the newly created case you can pass SkipCreateView as true in with parameters. Note:- To check how this activity has to be used, you can use CreateWorkFromEmail for the reference. CreateWorkFromEmail uses svcAddWorkObject  to create case in the backend.

But all these 3 activities basically in the background does the same-> Creates workPage and call AddWork to create a case in the background. Based on your additional requirements you can choose which activity to use.