Basically they are the same thing, since "square foot" implies a measure of surface area.
A "square foot", or "square feet," are units of measure, but they don't exactly say what they are measuring. A "square foot surface area" is both a unit of measure and a description of what you are measuring.
It's like saying "This is five inches", or "That is two gallons" without saying "this is five inches of length" or "that is two gallons of volume." The exact description is often unnecessary. "Square feet" is used since the object of measure is implied, and it is unlikely that they are used for anything other than units of area.
A "square foot", or "square feet," are units of measure, but they don't exactly say what they are measuring. A "square foot surface area" is both a unit of measure and a description of what you are measuring.
It's like saying "This is five inches", or "That is two gallons" without saying "this is five inches of length" or "that is two gallons of volume." The exact description is often unnecessary. "Square feet" is used since the object of measure is implied, and it is unlikely that they are used for anything other than units of area.