Pollen and nectar are both gathered from flowers. However, they are different substances and serve a different purpose for the bees. Nectar is a sugary liquid that flowers produce and bees use this to create honey. Honey is later eaten by bees as their carbohydrate source. Nectar also exists as a payment to get bees to land and unknowingly work for the plant. The plant ulterior motive is to get the bees to move some pollen around for it. (And to be honest it is not like the plant can move around much by itself.)
For spring we have removed the mouse guard from the hive entrance. It slows up bee traffic and right now it is rush hour. We also added the queen excluder and honey super to the top of the hive. The queen excluder is a plastic grate that is large enough for workers to pass through but not the queen. On top of this sits the honey super and then the lid and cover. The purpose of excluding the queen is to ensure that only honey and no egg/brood get placed in the honey super. The frames in this section are for human harvest.
While we are using the honey super we are not feeding any sugar syrup or pollen replacement. I doubt the bees really need either at the moment. Also, it is not recommended to use pollen replacement while honey supers are present.