All of them are synonyms for the stuff you can smell outside the Plaza Hotel.
The smell from the guns was everywhere inside the abandoned cannery.
You could feel it, smell it, run your hands over it, look across it.
late 12c., "emit or perceive an odor," not found in Old English, perhaps cognate with Middle Dutch smolen, Low German smelen "to smolder" (see smolder). However, OED says "no doubt of Old English origin, but not recorded, and not represented in any of the cognate languages." Related: Smelled or smelt; smelling.
Smelling salts (1840), used to revive the woozy, typically were a scented preparation of carbonate of ammonia. Smell-feast (n.) "one who finds and frequents good tables, one who scents out where free food is to be had" is from 1510s ("very common" c.1540-1700, OED). Smell-smock "licentious man" was in use c.1550-c.1900. To smell a rat "be suspicious" is from 1540s.
v. smelled or smelt (smělt), smell·ing, smells
To perceive the scent of something by means of the olfactory nerves. n.
The sense by which odors are perceived; the olfactory sense.