Ever been in this situation, you give a task to a member of your team and every few minutes the person would come back to you and ask you for feedback or queries and then you feel you are going nowhere with the task (as many a time you do not know the answers and would have to research) and the person feels that they have put in a lot of effort.
Alternatively you have the situation where you give a task to the member of your team, they understand what is the end goal of the task, they take all the inputs from you that you have to offer, go back to their desk and do all the research needed to execute, come back with a plan, resources needed and an activity list to execute the task and on approval sets about silently executing the task and only providing you periodic updates on the progress.
Which of these two team members would you prefer to work with? The answer is quite obvious and this is task execution vs task leadership. Its easy to find people who can execute tasks, but that leaves you to do all the thinking and making the plan. This slows down execution and can leave a lot of things on your desk waiting to be completed.
Find team members who can show leadership in understanding of what needs to be done and then doing whatever it takes to get it done rather than team members who can only execute what you give them to do. This is what differentiates a great team member from a good team member.