The reason these two words have different endings is because they grew from two different root words in Old French, which helped form Old (and Modern) English.
Intense came from the French word intensus, meaning "stretched, strained, tight".
Intensive came from the English word intend, which in turn came from the French words entendre and intendre (essentially the same word), which means "to direct one's attention to".
Interestingly, both of these French words have the same Latin root word intendere, which is literally "to stretch tight", but entendre took a separate path in terms of connotation and meaning and developed into the word we have now.
"Floor" can mean a level in a building, like "my office is on the second floor", or it can mean the part of the room that you stand on.
"Flooring" as a noun is the material you use to make a floor. In the U.S. these days -- I don't know about construction in other countries -- we usually buy flooring in tiles that are 1 foot square or thereabouts, or in strips that are maybe 2 or 3 feet long. Then you glue these to the raw wood or cement or whatever underneath. Or for carpet or tile you can buy a large roll so the flooring for the whole room will be one big piece.
"Floor" can also be a verb meaning to install such a floor.
When you're done, you can describe the floor by the type of flooring. So you could say, "We installed vinyl flooring so now we have a vinyl floor."
The second floor
Yes, the second level in the building in the U.S., the third level in the U.K.
The second floor I installed...
Yes, could be any kind of flooring.
Pine floor
A finished floor made from pine flooring.
Vinyl flooring
Vinyl material used to make a floor. You could say, "We installed vinyl flooring in the living room" or "The living room has vinyl flooring". Or you could say, "The living room has a vinyl floor." But you would not say, "The living room has a vinyl flooring."
I haven't done any flooring before
Yes, now it's a verb.
I floored the floor using vinyl flooring
Obviously an awkward sentence, but technically grammatically cored.
I used pine floor on the floor.
No, you'd say "I used pine flooring on the floor." Or more likely, "I put down pine flooring ..." or "I installed pine flooring ..." or "I laid down pine flooring ...".
The house has pine floors.
Yes.
The house has pine flooring.
Yes.
I'm flooring with pine flooring.
Yes. Again, use of the word "flooring" twice with two different meanings make the sentence awkward, but it's technically correct.
Best Answer
The word original works better when there is only one work in question:
The word genuine could work if we are talking about something that is not a forgery or a reproduction:
means that Manet painted it; it's not some facsimile of a Manet work.
In some contexts, either word could be used:
Both of those refer to a work created by Picasso's hand, although the first carries a slight connotation of "as opposed to a replica."