suelo vs. piso
What is the difference between suelo vs. piso? I have seen wet floor signs us piso but I also have seen the phrase ¨fregar el suelo¨ ' to mop the floor.
4 Answers
Having managed construction projects in Mexico, I've expierenced that a common uses of these terrms are:
Piso is used more for floors above the first floor. First floor of a multi-story building such as a hotel or apartment building is referred to as "planta baja". The upper floors are then segundo piso, tercero piso, etc. In a single story building, the ground floor is referred to as piso.
Suelo is used more to mean a surface of ground or dirt. When you want to do a geotchnical study of the soils. Is is called Estudio Mecanico del Suelo.
Perhaps this cross usage of these two words harkens back to days when most buildings had "dirt floors".
I suggest you search some of the threads that have been posted on the subject. There are a number of interpretations for the words, some of which are very much culture-dependent.
One example is that in Europe "piso" means apartment, whereas in much of Latin America "piso" means floor.
If you look at the local dictionary, however, you will see that there are a number of meanings to both words.
Tejero, the guy who tried to turn back democracy in Spain fired bullets into the roof and screamed ¡Todos al suelolink text
Todas al piso would mean Everyone back to (my) flat. 
as opposed to "Hit the dirt!"
The first definition in this dictionary say "interior pavement/floor" and the second definition is soil.(for suelo) For "piso" its first definition is related to the story of a building then the surface you walk on is second. From that I would derive they are interchangeable but suelo might be the more common first choice for where the dirt from your shoes lands.
