1. I won first prize in the English speech contest.

2. I won the first prize in the English speech contest.
--------------------------------
What is the difference between the two sentences?

3. I got a nice gift for my birthday.

4. I got a nice gift on my birthday.
-------------------------
In #4, 'on my birthday' is an adverbial phrase. Is that right?
What about in #3? Is 'for my birthday' an adverbial phrase or an adjective phrase? And then what is the use of 'for' in #3? What difference do the two sentences have because of different prepositions?

1 answer

1 and 2 -- both are fine.

3 means someone gave you a gift for your birthday, but doesn't specify when it was given to you.

4 means someone gave you a nice birthday gift on your actual birthday day!

Both prepositional phrases are adverbial.