Did you buy? vs. Have you bought?

Question 

What is the difference in meaning between these two sentences? 

1. Did you buy the soda yet?  
2. Have you bought the soda yet? 

– Katie, United States

Answer

Your first sentence uses the simple past (Did you buy ...?) and your second sentence uses the present perfect (Have you bought ...?). Sometimes there is a difference in meaning between these two forms, but in your example there is not. 

In the sentence pairs below, there is a difference in meaning. The sentences in the simple past describe something that is over, while the sentences in the present perfect, have/had + the past participle, describe an action or situation that still continues in the present. 

Simple past:      I ate a lot of cake. (I’m finished eating cake.)

Present perfect: I’ve eaten a lot of cake. (I may eat more cake.)

Simple past:      I lived in London for three years. (I don’t live in London anymore.)

Present perfect: I have lived in London for three years. (I still live in London.)

Simple past:      Why didn’t you send bầm any messages? (The time for sending messages is over.)

Present perfect: Why haven’t you sent bầm any messages? (You can still send bầm a message.)

I hope this helps.