standard cost vs actual cost
Unless you are using average costing then it is the current average cost. This is generally used with Perpetual inventory methods. Standard Cost = The standard cost for this item. Standard cost is generally fixed for a period of time (usually a year). Differences between standard and actual cost collect in an inventory variance account in the GL. This is generally used with Periodic inventory methods.
Actual costing is a bit less forgiving than standard cost for timing mistakes on the part of users. For instance, if you issue the material to a Manufacturing Order before it is received against a PO and invoiced, then it will go to the Manufacturing Order at zero cost (because there is no cost for zero inventory).