a. periscope & pyrometer
periscope is an optical instrument
pyrometer is a meter used to measure high temperature
b. cell & battery
Cell is a small unit/device that delivers an electric current as the result of a chemical reaction
Battery is a device that produces electricity having several cells arranged in parallel or series
c. perimeter & altimeter
perimeter is the outer boundary of a figure or area; total length of the outer boundary altimeter is an instrument for determining altitude attained, especially a barometric or radar device fitted in an aircraft.
d. pelage and plumage
pelage is growth of hair/fur/wool covering the skin of animals while plumage are feathers covering the body of birds
e. smog and smoke
Smog is formed by the interaction of pollutants present in the air in presence of sun light
(photochemical smog), it usually restricts visibility and is hazardous to health
Smoke are the thin fine particles usually result from the combustion