"FEWER" and "LESS"

"Fewer" is used for countable items. "Less" is used for uncountable quantities. Ex.: We need fewer chairs. There is less water in the bottle.

"CANVAS" and "CANVASS"

"Canvas" is a type of strong, heavy cloth. "Canvass" means to seek support or opinions, usually by going door to door. Ex.: The artist painted on a canvas. The politician will canvass the neighborhood for votes.