Hi Pradeep,

Flow-New is used when you want to specify the flow name directly.

Startflow or startnewflow is used if you need to specify a flow using a parameter or property reference.

CreateWorkProcess--This activity should be used by users who are accessing PRPC via services and need to create a new work object.  Do not use the activity if you are a harness based user.

This activity expects that the primary page is populated with all the required data to pass validation and create the work object.

Persistcase--Persist case is used when you have marked any flow as a temporary flow and want to persist after particular step.

Adding to my colleague's infor,

NewWork -

- Creates a work item, makes one assignment and adds a confirmation note attachment. 

- To review or work with a flow rule that creates a folder case, you can examine or test the standard flow rule PegaSample-Folder.NewWork. The following standard rules support folders:  

References:- https://pdn.pega.com/sites/pdn.pega.com/files/help_v722/procomhelpmain.htm#basics/portal/casemanager/cm-covers-and-folders-con.htm?Highlight=NewWork and https://pdn.pega.com/sites/pdn.pega.com/files/help_v722/procomhelpmain.htm#zstandardrules/rule-obj-flow.htm?Highlight=NewWork