Used to V and simple past tense.

[billmcd]

Of course there is a difference.
1-He used to swim in this river when he was young.

" Used to" describes something that happened regularly in the past but no longer happens today. The speaker in this example no longer swims in that river because it was just a past habit that no longer exists.
2-He often swam in this river when he was young.
The past simple, in contrast, simply situates something in the past. This person might still swim in that river today.

Just a comment with regard to #1, the addition of "when he was young" does not preclude the possibility that he still swims in the river. Without that phrase, I would agree that it is more likely to be a "habit that no longer exists." As usual, context rules.

[hoangkha]

Thank Mr.5jj, Ms.nedira and Mr.billmcd again.
Excuse me! I'd like all of you to give particular comments on this sentence (although I have mastered your previous comments) because it is in the E textbook in VN and I am in an argument now.
2- Last year I used to get up late. Now, I get up early and do morning exercises.

[billmcd]

Thank Mr.5jj, Ms.nedira and Mr.billmcd again.
Excuse me! I'd like all of you to give particular comments on this sentence (although I have mastered your previous comments) because it is in the E textbook in VN and I am in an argument now.
2- Last year I used to get up late. Now, I get up early and do morning exercises.

It's OK.

[hoangkha]

What about Mr.5jj, please?

[5jj]

2- Last year I used to get up late. Now, I get up early and do morning exercises.

It does not sound very natural to me, for reasons that I gave in post #7.

ps. I'm 5jj - no need for a 'Mr'.