DR position (dead reckoning position) is the position arrived after applying the true course steared and the distance by log ( called ships movement through water ) to a known starting position since the ship may have experienced effect of wind and current it may not actually be at DR position.
Estimated position (EP) – estimated position is the position arrive after applying the true course steered and the distance by log and also making allowance for an estimated direction and strength of wind and current experienced to known starting position since the effect of wind and current have been estimated the Ship may not actually be at the EP.
fix -fix is the actual position of the ship as obtained accurately by one or more means you are safe as you have obtained the position very certainty.
set & drift of current is the offset from the DR Position to the fix at that time.
Leeway – simple example of leeway, leeway the angle between the course steered and the angle of progress of the ship.