Dear srinandhat ,
you Don't need to confuse let me explain short and sweet
On NAV this kind of things control by "Permission set"
You can go to "Permission set" and see what are those
but your scenario , its better to create new permission set for those users
You can create a new permission set like "Create sale order" (you can name it as you want)
and assign required permission to that permission set "Create sale order"
then go to user card ==> permission set ==> map your new permission set and remove others
Make sure when you create new permission set you need to add following permission sets along with your new permission set
1. ADCS ALL
2. BASIC