Difference between Task Variable and Process Variable

[yogeshpj]

What is difference between task variable and process variable ? how can i use them in WorkflowTaskQuery?

[mrogers]

A workflow instance contains one or more tasks.    Process variables apply to the entire instance of a workflow, task variables apply to a single task.     At the beginning and end of each task you can map your task variables to process variables according to the needs of your workflow.

[yogeshpj]

Thanks mrogers,

         The  variable which are declared in process defination are process instance variable which can be use throughout the process and task variables are variables which are declared in workflow model  under task type.correct me if i am wrong. And  how can i use them in WorkflowTaskQuery ? WorkflowTaskQuery provide two facilities one is taskCustomProps and second is processCustomProps. when i am firing query in which i have set task varialbes (which are declared on workflow model) in taskCustomProps but i am not getting the result. But when i am firing query in which i have set processCustomProps  then i am getting the result. I dont know why this happens ?. Can you plz help me to figure out this?