New build apartments - price per sq metre/foot

[Lily70]

I understand that the higher the number of floors in the building the more it costs to build. However, I am not sure why some developers add £5,000 per flat price for each floor and some add £10,000.

Also, is there a reason why in similar-ish one-bedroom flats on the same floor, price per square metre varies?
For example: two flats 50 sq.m each, one facing the adjacent building is £100 cheaper per sq. me than the other flat facing the road.
Another example, in a slightly bigger, 53 sq. m flat on the rear of the building, facing south-west, price per sq.m is £50 less than in a 50 sq.m flat facing north and looking at the road.

Is there a reason behind variance in price per sq.m. of same type flat on the same floor, or there is some limit on the total price of a flat that matters?

[New Home Expert]

House builders will always price the homes they build at the maximum they believe they can get for them.
Flats on the same floor will have different aspects and views. Some will get sun, some less or no sun.
Some will have views that are better than others.  Some will be near lifts and stairs (more noisy) than others.  
All of these factors make the same size flat on the same floor more or less desirable to buyers and this is being reflected in the price.

It does indeed cost more to build more floors.  After three floors a lift is essential.
There are also more fire regulations to implement.  
But the cost of these is more than covered by the extra homes sold as it is the land that can account for up to a third of the property price.
Quite why this developer is increasing prices the higher up the block a flat is, can only be to do with the view.

[Lily70]

Thank you very much, NHE, for detailed reply!