✅ Immediately means without delay, happening right now (She called him immediately after the meeting).

✅ Straightaway means at once or without hesitation (He answered the question straightaway).

✅ Both words describe something happening right away.

✅ Immediately is more widely used and often refers to promptness and exact timing involving urgent situations, while straightaway is more informal and relaxed, often heard in British English (When the fire alarm sounded, we evacuated the building immediately; I'll start the project straightaway).

✅ Rickety means unstable or likely to collapse, especially due to old or poor construction (The rickety chair wobbled dangerously).

✅ Decrepit means worn out or weakened by age, and can refer to both people and objects (The decrepit house was barely standing).

✅ Both words describe things that are old and in poor condition.

✅ Rickety is more often used for an object's physical instability, while decrepit can refer to wider physical weaknesses such as deterioration and aging.

✅ Rot means to decay or break down, often in an unpleasant or smelly way (The fruit began to rot in the hot sun).

✅ Decompose refers to the breakdown of organic material, often by bacteria or fungi (The fallen leaves decompose on the forest floor).

✅ Both words describe organic decay.

✅ Rot is more commonly used in casual contexts for foul odors or sights, while decompose is more scientific and suggests a technical process that can happen on a molecular or chemical level (The old food rotted in the fridge; In the compost bin, food scraps slowly decompose into nutrient-rich soil).