"EFFECT" and "AFFECT"

"Effect" is a noun meaning result. "Affect" is a verb meaning to influence. Ex.: The new policy had a significant effect. The weather can affect our mood.

"STATIONARY" and "STATIONERY"

"Stationary" means not moving or not changing. "Stationery" refers to writing materials, such as paper, pens, and envelopes. Ex.: The car remained stationary at the traffic light. I need to buy some stationery for the office.